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Fontbakery report

Fontbakery version: 0.7.27

[14] Family checks
ℹ INFO: Do we have the latest version of FontBakery installed?
🍞 PASS: Ensure that all variable font files have the same set of axes and axis ranges. 
--- Rationale ---

In order to facilitate the construction of intuitive and friendly user
interfaces, all variable font files in a given family should have the same set
of variation axes. Also, each axis must have a consistent setting of min/max
value ranges accross all the files.
  • 🍞 PASS All looks good!
🍞 PASS: Does font file include unacceptable control character glyphs? 
--- Rationale ---

Use of some unacceptable control characters in the U+0000 - U+001F range can
lead to rendering issues on some platforms.

Acceptable control characters are defined as .null (U+0000) and CR (U+000D) for
this test.
  • 🍞 PASS Unacceptable control characters were not identified.
🍞 PASS: Checking all files are in the same directory. 
--- Rationale ---

If the set of font files passed in the command line is not all in the same
directory, then we warn the user since the tool will interpret the set of files
as belonging to a single family (and it is unlikely that the user would store
the files from a single family spreaded in several separate directories).
  • 🍞 PASS All files are in the same directory.
🍞 PASS: Is the command `ftxvalidator` (Apple Font Tool Suite) available? 
--- Rationale ---

There's no reasonable (and legal) way to run the command `ftxvalidator` of the
Apple Font Tool Suite on a non-macOS machine. I.e. on GNU+Linux or Windows etc.

If Font Bakery is not running on an OSX machine, the machine running Font
Bakery could access `ftxvalidator` on OSX, e.g. via ssh or a remote procedure
call (rpc).

There's an ssh example implementation at:
https://github.com/googlefonts/fontbakery/blob/master/prebuilt/workarounds
/ftxvalidator/ssh-implementation/ftxvalidator
  • 🍞 PASS ftxvalidator is available at /usr/local/bin/ftxvalidator
🍞 PASS: Each font in a family must have the same set of vertical metrics values. 
--- Rationale ---

We want all fonts within a family to have the same vertical metrics so their
line spacing is consistent across the family.
  • 🍞 PASS Vertical metrics are the same across the family.
🍞 PASS: Fonts have equal unicode encodings?
🍞 PASS: Make sure all font files have the same version value.
🍞 PASS: Fonts have consistent PANOSE proportion?
🍞 PASS: Fonts have consistent PANOSE family type?
🍞 PASS: Fonts have consistent underline thickness? 
--- Rationale ---

Dave C Lemon (Adobe Type Team) recommends setting the underline thickness to be
consistent across the family.

If thicknesses are not family consistent, words set on the same line which have
different styles look strange.

See also:
https://twitter.com/typenerd1/status/690361887926697986
  • 🍞 PASS Fonts have consistent underline thickness.
🍞 PASS: Verify that each group of fonts with the same nameID 1 has maximum of 4 fonts 
--- Rationale ---

Per the OpenType spec:
'The Font Family name ... should be shared among at most four fonts that differ
only in weight or style ...'
  • 🍞 PASS There were no more than 4 fonts per family name.
💤 SKIP: All tabular figures must have the same width across the RIBBI-family. 
--- Rationale ---

Tabular figures need to have the same metrics in all styles in order to allow
tables to be set with proper typographic control, but to maintain the placement
of decimals and numeric columns between rows.

Here's a good explanation of this:
https://www.typography.com/techniques/fonts-for-financials/#tabular-figs
  • 💤 SKIP Unfulfilled Conditions: RIBBI_ttFonts
💤 SKIP: Check that OS/2.fsSelection bold & italic settings are unique for each NameID1 
--- Rationale ---

Per the OpenType spec: name ID 1 'is used in combination with Font Subfamily
name (name ID 2), and should be shared among at most four fonts that differ
only in weight or style...

This four-way distinction should also be reflected in the OS/2.fsSelection
field, using bits 0 and 5.
  • 💤 SKIP Unfulfilled Conditions: RIBBI_ttFonts

[161] EncodeSansSC[wdth,wght].ttf
💔 ERROR: Version number has increased since previous release on Google Fonts?

  • com.google.fonts/check/version_bump

  • 💔 ERROR The condition FontBakeryCondition:github_gfonts_ttFont had an error: BadCertificateSetupException: You probably installed official Mac python from python.org but forgot to also install the certificates. There is a note in the installer Readme about that. Check the Python folder in the Applications directory, you should find a shell script to install the certificates.

🔥 FAIL: Name table strings must not contain the string 'Reserved Font Name'. 
--- Rationale ---

Some designers adopt the "Reserved Font Name" clause of the OFL license. This
means that the original author reserves the rights to the family name and other
people can only distribute modified versions using a different family name.

Google Fonts published updates to the fonts in the collection in order to fix
issues and/or implement further improvements to the fonts. It is important to
keep the family name so that users of the webfonts can benefit from the
updates. Since it would forbid such usage scenario, all families in the GFonts
collection are required to not adopt the RFN clause.

This check ensures "Reserved Font Name" is not mentioned in the name table.
  • 🔥 FAIL Name table entry ("Copyright 2020 The Encode Project Authors (https://github.com/thundernixon/Encode-Sans), with Reserved Font Name 'Encode Sans'.") contains "Reserved Font Name". This is an error except in a few specific rare cases. [code: rfn]
⚠ WARN: METADATA.pb: Fontfamily is listed on Google Fonts API?
⚠ WARN: Copyright notice on METADATA.pb should not contain 'Reserved Font Name'.
⚠ WARN: Combined length of family and style must not exceed 27 characters. 
--- Rationale ---

According to a GlyphsApp tutorial [1], in order to make sure all versions of
Windows recognize it as a valid font file, we must make sure that the
concatenated length of the familyname (NameID.FONT_FAMILY_NAME) and style
(NameID.FONT_SUBFAMILY_NAME) strings in the name table do not exceed 20
characters.

After discussing the problem in more detail at `FontBakery issue #2179 [2] we
decided that allowing up to 27 chars would still be on the safe side, though.

[1]
https://glyphsapp.com/tutorials/multiple-masters-part-3-setting-up-instances
[2] https://github.com/googlefonts/fontbakery/issues/2179
  • ⚠ WARN The combined length of family and style exceeds 27 chars in the following 'WINDOWS' entries: FONT_FAMILY_NAME = 'Encode Sans SC Cnd Th' / SUBFAMILY_NAME = 'Regular'

Please take a look at the conversation at fonttools/fontbakery#2179 in order to understand the reasoning behind these name table records max-length criteria. [code: too-long]

💤 SKIP: Font has ttfautohint params?
💤 SKIP: METADATA.pb font.name value should be same as the family name declared on the name table.
💤 SKIP: METADATA.pb font.filename and font.post_script_name fields have equivalent values?
💤 SKIP: METADATA.pb font.name field contains font name in right format?
💤 SKIP: METADATA.pb font.full_name field contains font name in right format?
💤 SKIP: METADATA.pb font.filename field contains font name in right format?
💤 SKIP: METADATA.pb font.style "italic" matches font internals?
💤 SKIP: METADATA.pb weight matches postScriptName for static fonts.
💤 SKIP: Glyphs are similiar to Google Fonts version?
💤 SKIP: Checking OS/2 fsSelection value.
💤 SKIP: Checking post.italicAngle value. 
--- Rationale ---

The 'post' table italicAngle property should be a reasonable amount, likely not
more than -20°, never more than -30°, and never greater than 0°. Note that in
the OpenType specification, the value is negative for a lean rightwards.

https://docs.microsoft.com/en-us/typography/opentype/spec/post
  • 💤 SKIP Unfulfilled Conditions: style
💤 SKIP: Checking head.macStyle value. 
--- Rationale ---

The values of the flags on the macStyle entry on the 'head' OpenType table that
describe whether a font is bold and/or italic must be coherent with the actual
style of the font as inferred by its filename.
  • 💤 SKIP Unfulfilled Conditions: style
💤 SKIP: Check if each glyph has the recommended amount of contours. 
--- Rationale ---

Visually QAing thousands of glyphs by hand is tiring. Most glyphs can only be
constructured in a handful of ways. This means a glyph's contour count will
only differ slightly amongst different fonts, e.g a 'g' could either be 2 or 3
contours, depending on whether its double story or single story.

However, a quotedbl should have 2 contours, unless the font belongs to a
display family.

This check currently does not cover variable fonts because there's plenty of
alternative ways of constructing glyphs with multiple outlines for each feature
in a VarFont. The expected contour count data for this check is currently
optimized for the typical construction of glyphs in static fonts.
  • 💤 SKIP Unfulfilled Conditions: not is_variable_font
💤 SKIP: Font has all mandatory 'name' table entries?
💤 SKIP: Check name table: FONT_FAMILY_NAME entries. 
--- Rationale ---

Checks that the family name infered from the font filename matches the string
at nameID 1 (NAMEID_FONT_FAMILY_NAME) if it conforms to RIBBI and otherwise
checks that nameID 1 is the family name + the style name.
  • 💤 SKIP Unfulfilled Conditions: style
💤 SKIP: Check name table: FULL_FONT_NAME entries.
💤 SKIP: Check name table: POSTSCRIPT_NAME entries.
💤 SKIP: Check name table: TYPOGRAPHIC_FAMILY_NAME entries.
💤 SKIP: PPEM must be an integer on hinted fonts. 
--- Rationale ---

Hinted fonts must have head table flag bit 3 set.

Per https://docs.microsoft.com/en-us/typography/opentype/spec/head, bit 3 of
Head::flags decides whether PPEM should be rounded. This bit should always be
set for hinted fonts.

Note:
Bit 3 = Force ppem to integer values for all internal scaler math;
        May use fractional ppem sizes if this bit is clear;
  • 💤 SKIP Unfulfilled Conditions: is_hinted
💤 SKIP: Are there caret positions declared for every ligature? 
--- Rationale ---

All ligatures in a font must have corresponding caret (text cursor) positions
defined in the GDEF table, otherwhise, users may experience issues with caret
rendering.
  • 💤 SKIP Unfulfilled Conditions: ligature_glyphs
💤 SKIP: Is there kerning info for non-ligated sequences? 
--- Rationale ---

Fonts with ligatures should have kerning on the corresponding non-ligated
sequences for text where ligatures aren't used (eg
https://github.com/impallari/Raleway/issues/14).
  • 💤 SKIP Unfulfilled Conditions: ligatures
💤 SKIP: Directory name in GFonts repo structure must match NameID 1 of the regular.
💤 SKIP: Check if the vertical metrics of a family are similar to the same family hosted on Google Fonts. 
--- Rationale ---

If the family already exists on Google Fonts, we need to ensure that the
checked family's vertical metrics are similar. This check will test the
following schema which was outlined in Fontbakery issue #1162 [1]:

- The family should visually have the same vertical metrics as the
  Regular style hosted on Google Fonts.
- If the family on Google Fonts has differing hhea and typo metrics,
  the family being checked should use the typo metrics for both the
  hhea and typo entries.
- If the family on Google Fonts has use typo metrics not enabled and the
  family being checked has it enabled, the hhea and typo metrics
  should use the family on Google Fonts winAscent and winDescent values.
- If the upms differ, the values must be scaled so the visual appearance
  is the same.

[1] https://github.com/googlefonts/fontbakery/issues/1162
  • 💤 SKIP Unfulfilled Conditions: remote_styles
💤 SKIP: Check font follows the Google Fonts CJK vertical metric schema 
--- Rationale ---

CJK fonts have different vertical metrics when compared to Latin fonts. We
follow the schema developed by dr Ken Lunde for Source Han Sans and the Noto
CJK fonts.

Our documentation includes further information:
https://github.com/googlefonts/gf-docs/tree/master/Spec#cjk-vertical-metrics
  • 💤 SKIP Unfulfilled Conditions: is_cjk_font
💤 SKIP: Is the CFF subr/gsubr call depth > 10? 
--- Rationale ---

Per "The Type 2 Charstring Format, Technical Note #5177", the "Subr nesting,
stack limit" is 10.
  • 💤 SKIP Unfulfilled Conditions: is_cff
💤 SKIP: Is the CFF2 subr/gsubr call depth > 10? 
--- Rationale ---

Per "The CFF2 CharString Format", the "Subr nesting, stack limit" is 10.
  • 💤 SKIP Unfulfilled Conditions: is_cff2
💤 SKIP: CFF table FontName must match name table ID 6 (PostScript name). 
--- Rationale ---

The PostScript name entries in the font's 'name' table should match the
FontName string in the 'CFF ' table.

The 'CFF ' table has a lot of information that is duplicated in other tables.
This information should be consistent across tables, because there's no
guarantee which table an app will get the data from.
  • 💤 SKIP Unfulfilled Conditions: is_cff
💤 SKIP: The variable font 'slnt' (Slant) axis coordinate must be zero on the 'Regular' instance. 
--- Rationale ---

According to the Open-Type spec's registered design-variation tag 'slnt'
available at
https://docs.microsoft.com/en-gb/typography/opentype/spec/dvaraxistag_slnt

If a variable font has a 'slnt' (Slant) axis, then the coordinate of its
'Regular' instance is required to be zero.
  • 💤 SKIP Unfulfilled Conditions: regular_slnt_coord
💤 SKIP: The variable font 'ital' (Italic) axis coordinate must be zero on the 'Regular' instance. 
--- Rationale ---

According to the Open-Type spec's registered design-variation tag 'ital'
available at
https://docs.microsoft.com/en-gb/typography/opentype/spec/dvaraxistag_ital

If a variable font has a 'ital' (Italic) axis, then the coordinate of its
'Regular' instance is required to be zero.
  • 💤 SKIP Unfulfilled Conditions: regular_ital_coord
💤 SKIP: The variable font 'opsz' (Optical Size) axis coordinate should be between 9 and 13 on the 'Regular' instance. 
--- Rationale ---

According to the Open-Type spec's registered design-variation tag 'opsz'
available at
https://docs.microsoft.com/en-gb/typography/opentype/spec/dvaraxistag_opsz

If a variable font has a 'opsz' (Optical Size) axis, then the coordinate of its
'Regular' instance is recommended to be a value in the range 9 to 13.
  • 💤 SKIP Unfulfilled Conditions: regular_opsz_coord
💤 SKIP: The variable font 'slnt' (Slant) axis coordinate specifies positive values in its range? 
--- Rationale ---

The OpenType spec says at
https://docs.microsoft.com/en-us/typography/opentype/spec/dvaraxistag_slnt
that:

[...] the scale for the Slant axis is interpreted as the angle of slant in
counter-clockwise degrees from upright. This means that a typical,
right-leaning oblique design will have a negative slant value. This matches the
scale used for the italicAngle field in the post table.
  • 💤 SKIP Unfulfilled Conditions: slnt_axis
ℹ INFO: Does DESCRIPTION file contain a upstream Git repo URL? 
--- Rationale ---

The contents of the DESCRIPTION.en-us.html file are displayed on the Google
Fonts website in the about section of each font family specimen page.

Since all of the Google Fonts collection is composed of libre-licensed fonts,
this check enforces a policy that there must be a hypertext link in that page
directing users to the repository where the font project files are made
available.

Such hosting is typically done on sites like Github, Gitlab, GNU Savannah or
any other git-based version control service.
ℹ INFO: Show hinting filesize impact. 
--- Rationale ---

This check is merely informative, displaying and useful comparison of filesizes
of hinted versus unhinted font files.

  • ℹ INFO Hinting filesize impact:

    /Users/stephennixon/type-repos/google-font-repos/fonts/ofl/encodesanssc/EncodeSansSC[wdth,wght].ttf
    Dehinted Size 213.4kb
    Hinted Size 212.4kb
    Increase -1040 bytes
    Change -0.5 %

[code: size-impact]

ℹ INFO: Font has old ttfautohint applied? 
--- Rationale ---

This check finds which version of ttfautohint was used, by inspecting name
table entries and then finds which version of ttfautohint is currently
installed in the system.
  • ℹ INFO Could not detect which version of ttfautohint was used in this font. It is typically specified as a comment in the font version entries of the 'name' table. Such font version strings are currently: ['Version 3.000'] [code: version-not-detected]
ℹ INFO: EPAR table present in font? 
--- Rationale ---

The EPAR table is/was a way of expressing common licensing permissions and
restrictions in metadata; while almost nothing supported it, Dave Crossland
wonders that adding it to everything in Google Fonts could help make it more
popular.

More info is available at:
https://davelab6.github.io/epar/
ℹ INFO: Is the Grid-fitting and Scan-conversion Procedure ('gasp') table set to optimize rendering? 
--- Rationale ---

Traditionally version 0 'gasp' tables were set so that font sizes below 8 ppem
had no grid fitting but did have antialiasing. From 9-16 ppem, just grid
fitting. And fonts above 17ppem had both antialiasing and grid fitting toggled
on. The use of accelerated graphics cards and higher resolution screens make
this approach obsolete. Microsoft's DirectWrite pushed this even further with
much improved rendering built into the OS and apps.

In this scenario it makes sense to simply toggle all 4 flags ON for all font
sizes.
  • ℹ INFO These are the ppm ranges declared on the gasp table:

PPM <= 65535: flag = 0x0F - Use grid-fitting - Use grayscale rendering - Use gridfitting with ClearType symmetric smoothing - Use smoothing along multiple axes with ClearType® [code: ranges]

  • 🍞 PASS The 'gasp' table is correctly set, with one gaspRange:value of 0xFFFF:0x0F.
ℹ INFO: Check for font-v versioning. 
--- Rationale ---

The git sha1 tagging and dev/release features of Source Foundry `font-v` tool
are awesome and we would love to consider upstreaming the approach into
fontmake someday. For now we only emit a WARN if a given font does not yet
follow the experimental versioning style, but at some point we may start
enforcing it.
  • ℹ INFO Version string is: "Version 3.000" The version string must ideally include a git commit hash and either a "dev" or a "release" suffix such as in the example below: "Version 1.3; git-0d08353-release" [code: bad-format]
ℹ INFO: Font contains all required tables? 
--- Rationale ---

Depending on the typeface and coverage of a font, certain tables are
recommended for optimum quality. For example, the performance of a non-linear
font is improved if the VDMX, LTSH, and hdmx tables are present. Non-monospaced
Latin fonts should have a kern table. A gasp table is necessary if a designer
wants to influence the sizes at which grayscaling is used under Windows. A DSIG
table containing a digital signature helps ensure the integrity of the font
file. Etc.
  • ℹ INFO This font contains the following optional tables [GSUB, DSIG, loca, prep, gasp, GPOS]
  • 🍞 PASS Font contains all required tables.
ℹ INFO: List all superfamily filepaths 
--- Rationale ---

This is a merely informative check that lists all sibling families detected by
fontbakery.

Only the fontfiles in these directories will be considered in superfamily-level
checks.
  • ℹ INFO /Users/stephennixon/type-repos/google-font-repos/fonts/ofl/encodesans [code: family-path]
  • ℹ INFO /Users/stephennixon/type-repos/google-font-repos/fonts/ofl/encodesanssc [code: family-path]
  • ℹ INFO /Users/stephennixon/type-repos/google-font-repos/fonts/ofl/encodesanscondensed [code: family-path]
🍞 PASS: Checking file is named canonically. 
--- Rationale ---

A font's filename must be composed in the following manner:
<familyname>-<stylename>.ttf

- Nunito-Regular.ttf,
- Oswald-BoldItalic.ttf

Variable fonts must list the axis tags in alphabetical order in square brackets
and separated by commas:

- Roboto[wdth,wght].ttf
- Familyname-Italic[wght].ttf
  • 🍞 PASS /Users/stephennixon/type-repos/google-font-repos/fonts/ofl/encodesanssc/EncodeSansSC[wdth,wght].ttf is named canonically.
🍞 PASS: Does DESCRIPTION file contain broken links? 
--- Rationale ---

The snippet of HTML in the DESCRIPTION.en_us.html file is added to the font
family webpage on the Google Fonts website. For that reason, all hyperlinks in
it must be properly working.
  • 🍞 PASS All links in the DESCRIPTION file look good!
🍞 PASS: Is this a proper HTML snippet? 
--- Rationale ---

When packaging families for being pushed to the `google/fonts` git repo, if
there is no DESCRIPTION.en_us.html file, some older versions of the
`add_font.py` tool insert a dummy description file which contains invalid html.

This file needs to either be replaced with an existing description file or
edited by hand.
  • 🍞 PASS /Users/stephennixon/type-repos/google-font-repos/fonts/ofl/encodesanssc/DESCRIPTION.en_us.html is a propper HTML file.
🍞 PASS: DESCRIPTION.en_us.html must have more than 200 bytes.
🍞 PASS: DESCRIPTION.en_us.html must have less than 1000 bytes.
🍞 PASS: DESCRIPTION.en_us.html should end in a linebreak. 
--- Rationale ---

Some older text-handling tools sometimes misbehave if the last line of data in
a text file is not terminated with a newline character (also known as '\n').

We know that this is a very small detail, but for the sake of keeping all
DESCRIPTION.en_us.html files uniformly formatted throughout the GFonts
collection, we chose to adopt the practice of placing this final linebreak char
on them.
  • 🍞 PASS :-)
🍞 PASS: Check METADATA.pb parse correctly. 
--- Rationale ---

The purpose of this check is to ensure that the METADATA.pb file is not
malformed.
  • 🍞 PASS METADATA.pb parsed successfuly.
🍞 PASS: Font designer field in METADATA.pb must not be 'unknown'.
🍞 PASS: Font designer field in METADATA.pb must not contain 'Multiple designers'. 
--- Rationale ---

For a while the string "Multiple designers" was used as a placeholder on
METADATA.pb files. We should replace all those instances with actual designer
names so that proper credits are displayed on the Google Fonts family specimen
pages.

If there's more than a single designer, the designer names must be separated by
commas.
  • 🍞 PASS Looks good.
🍞 PASS: Multiple values in font designer field in METADATA.pb must be separated by commas. 
--- Rationale ---

We must use commas instead of forward slashes because the server-side code at
the fonts.google.com directory will segment the string on the commas into a
list of names and display the first item in the list as the "principal
designer" while the remaining names are identified as "contributors".

See eg https://fonts.google.com/specimen/Rubik
  • 🍞 PASS Looks good.
🍞 PASS: Does METADATA.pb copyright field contain broken links?
🍞 PASS: Ensure METADATA.pb lists all font binaries. 
--- Rationale ---

The set of font binaries available, except the ones on a "static" subdir, must
match exactly those declared on the METADATA.pb file.

Also, to avoid confusion, we expect that font files (other than statics) are
not placed on subdirectories.
  • 🍞 PASS OK
🍞 PASS: Checking OS/2 fsType does not impose restrictions. 
--- Rationale ---

The fsType in the OS/2 table is a legacy DRM-related field. Fonts in the Google
Fonts collection must have it set to zero (also known as "Installable
Embedding"). This setting indicates that the fonts can be embedded in documents
and permanently installed by applications on remote systems.

More detailed info is available at:
https://docs.microsoft.com/en-us/typography/opentype/spec/os2#fstype
  • 🍞 PASS OS/2 fsType is properly set to zero.
🍞 PASS: Checking OS/2 achVendID. 
--- Rationale ---

Microsoft keeps a list of font vendors and their respective contact info. This
list is updated regularly and is indexed by a 4-char "Vendor ID" which is
stored in the achVendID field of the OS/2 table.

Registering your ID is not mandatory, but it is a good practice since some
applications may display the type designer / type foundry contact info on some
dialog and also because that info will be visible on Microsoft's website:

https://docs.microsoft.com/en-us/typography/vendors/

This check verifies whether or not a given font's vendor ID is registered in
that list or if it has some of the default values used by the most common font
editors.

Each new FontBakery release includes a cached copy of that list of vendor IDs.
If you registered recently, you're safe to ignore warnings emitted by this
check, since your ID will soon be included in one of our upcoming releases.
  • 🍞 PASS OS/2 VendorID 'GOOG' looks good!
🍞 PASS: Check `Google Fonts Latin Core` glyph coverage. 
--- Rationale ---

Google Fonts expects that fonts in its collection support at least the minimal
set of characters defined in the `GF-latin-core` glyph-set.
  • 🍞 PASS OK
🍞 PASS: Substitute copyright, registered and trademark symbols in name table entries.
🍞 PASS: Checking OS/2 usWeightClass. 
--- Rationale ---

Google Fonts expects variable fonts, static ttfs and static otfs to have
differing OS/2 usWeightClass values.

For Variable Fonts, Thin-Black must be 100-900
For static ttfs, Thin-Black can be 100-900 or 250-900
For static otfs, Thin-Black must be 250-900

If static otfs are set lower than 250, text may appear blurry in legacy Windows
applications.

Glyphsapp users can change the usWeightClass value of an instance by adding a
'weightClass' customParameter.
  • 🍞 PASS OS/2 usWeightClass is good
🍞 PASS: Check font has a license.
🍞 PASS: Check license file has good copyright string. 
--- Rationale ---

An OFL.txt file's first line should be the font copyright e.g:
"Copyright 2019 The Montserrat Project Authors
(https://github.com/julietaula/montserrat)"
  • 🍞 PASS looks good
🍞 PASS: Check copyright namerecords match license file. 
--- Rationale ---

A known licensing description must be provided in the NameID 14 (LICENSE
DESCRIPTION) entries of the name table.

The source of truth for this check (to determine which license is in use) is a
file placed side-by-side to your font project including the licensing terms.

Depending on the chosen license, one of the following string snippets is
expected to be found on the NameID 13 (LICENSE DESCRIPTION) entries of the name
table:
- "This Font Software is licensed under the SIL Open Font License, Version 1.1.
This license is available with a FAQ at: https://scripts.sil.org/OFL"
- "Licensed under the Apache License, Version 2.0"
- "Licensed under the Ubuntu Font Licence 1.0."


Currently accepted licenses are Apache or Open Font License.
For a small set of legacy families the Ubuntu Font License may be acceptable as
well.

When in doubt, please choose OFL for new font projects.
  • 🍞 PASS Licensing entry on name table is correctly set.
🍞 PASS: License URL matches License text on name table? 
--- Rationale ---

A known license URL must be provided in the NameID 14 (LICENSE INFO URL) entry
of the name table.

The source of truth for this check is the licensing text found on the NameID 13
entry (LICENSE DESCRIPTION).

The string snippets used for detecting licensing terms are:
- "This Font Software is licensed under the SIL Open Font License, Version 1.1.
This license is available with a FAQ at: https://scripts.sil.org/OFL"
- "Licensed under the Apache License, Version 2.0"
- "Licensed under the Ubuntu Font Licence 1.0."


Currently accepted licenses are Apache or Open Font License.
For a small set of legacy families the Ubuntu Font License may be acceptable as
well.

When in doubt, please choose OFL for new font projects.
  • 🍞 PASS Font has a valid license URL in NAME table.
🍞 PASS: Description strings in the name table must not exceed 200 characters. 
--- Rationale ---

An old FontLab version had a bug which caused it to store copyright notices in
nameID 10 entries.

In order to detect those and distinguish them from actual legitimate usage of
this name table entry, we expect that such strings do not exceed a reasonable
length of 200 chars.

Longer strings are likely instances of the FontLab bug.
  • 🍞 PASS All description name records have reasonably small lengths.
🍞 PASS: Version format is correct in 'name' table?
🍞 PASS: Make sure family name does not begin with a digit. 
--- Rationale ---

Font family names which start with a numeral are often not discoverable in
Windows applications.
  • 🍞 PASS Font family name first character is not a digit.
🍞 PASS: Are there non-ASCII characters in ASCII-only NAME table entries? 
--- Rationale ---

The OpenType spec requires ASCII for the POSTSCRIPT_NAME (nameID 6).

For COPYRIGHT_NOTICE (nameID 0) ASCII is required because that string should be
the same in CFF fonts which also have this requirement in the OpenType spec.

Note:
A common place where we find non-ASCII strings is on name table entries with
NameID > 18, which are expressly for localising the ASCII-only IDs into Hindi /
Arabic / etc.
  • 🍞 PASS None of the ASCII-only NAME table entries contain non-ASCII characteres.
🍞 PASS: METADATA.pb: check if fonts field only has unique "full_name" values.
🍞 PASS: METADATA.pb: check if fonts field only contains unique style:weight pairs.
🍞 PASS: METADATA.pb license is "APACHE2", "UFL" or "OFL"?
🍞 PASS: METADATA.pb should contain at least "menu" and "latin" subsets.
🍞 PASS: METADATA.pb subsets should be alphabetically ordered.
🍞 PASS: METADATA.pb: Copyright notice is the same in all fonts?
🍞 PASS: Check that METADATA.pb family values are all the same.
🍞 PASS: METADATA.pb: According Google Fonts standards, families should have a Regular style.
🍞 PASS: METADATA.pb: Regular should be 400.
🍞 PASS: Checks METADATA.pb font.name field matches family name declared on the name table.
🍞 PASS: Checks METADATA.pb font.post_script_name matches postscript name declared on the name table.
🍞 PASS: METADATA.pb font.full_name value matches fullname declared on the name table?

  • com.google.fonts/check/metadata/nameid/full_name

  • 🍞 PASS Font fullname "Encode Sans SC Cnd Th" is identical in METADATA.pb and on the TTF file.

  • 🍞 PASS Font fullname "Encode Sans SC Cnd Th" is identical in METADATA.pb and on the TTF file.

🍞 PASS: METADATA.pb font.full_name and font.post_script_name fields have equivalent values ?
🍞 PASS: METADATA.pb font.post_script_name field contains font name in right format?
🍞 PASS: Copyright notices match canonical pattern in METADATA.pb 
--- Rationale ---

The expected pattern for the copyright string adheres to the following rules:
* It must say "Copyright" followed by a 4 digit year (optionally followed by a
hyphen and another 4 digit year)
* Then it must say "The <familyname> Project Authors"
* And within parentheses, a URL for a git repository must be provided
* The check is case insensitive and does not validate whether the familyname is
correct, even though we'd expect it is (and we may soon update the check to
validate that aspect as well!)

Here is an example of a valid copyright string:
"Copyright 2017 The Archivo Black Project Authors
(https://github.com/Omnibus-Type/ArchivoBlack)"
  • 🍞 PASS METADATA.pb copyright string is good
🍞 PASS: Copyright notices match canonical pattern in fonts
🍞 PASS: METADATA.pb: Copyright notice shouldn't exceed 500 chars.
🍞 PASS: METADATA.pb: Font filenames match font.filename entries? 
--- Rationale ---

Note:
This check only looks for files in the current directory.

Font files in subdirectories are checked by these other two checks:
 - com.google.fonts/check/metadata/undeclared_fonts
 - com.google.fonts/check/repo/vf_has_static_fonts

We may want to merge them all into a single check.
  • 🍞 PASS Filenames in METADATA.pb look good.
🍞 PASS: METADATA.pb font.style "normal" matches font internals?
🍞 PASS: METADATA.pb font.name and font.full_name fields match the values declared on the name table?
🍞 PASS: METADATA.pb: Check if fontname is not camel cased.
🍞 PASS: METADATA.pb: Check font name is the same as family name.
🍞 PASS: METADATA.pb: Check that font weight has a canonical value.
🍞 PASS: Check METADATA.pb font weights are correct. 
--- Rationale ---

Check METADATA.pb font weights are correct.

For static fonts, the metadata weight should be the same
as the static font's OS/2 usWeightClass.

For variable fonts, the weight value should be 400 if the
font's wght axis range includes 400, otherwise it should be the
value closest to 400.
  • 🍞 PASS OS/2 usWeightClass or wght axis value matches weight specified at METADATA.pb
🍞 PASS: METADATA.pb: Font styles are named canonically?
🍞 PASS: Stricter unitsPerEm criteria for Google Fonts. 
--- Rationale ---

Even though the OpenType spec allows unitsPerEm to be any value between 16 and
16384, the Google Fonts project aims at a narrower set of reasonable values.

The spec suggests usage of powers of two in order to get some performance
improvements on legacy renderers, so those values are acceptable.

But value of 500 or 1000 are also acceptable, with the added benefit that it
makes upm math easier for designers, while the performance hit of not using a
power of two is most likely negligible nowadays.

Another acceptable value is 2000. Since TT outlines are all integers (no
floats), then instances in a VF suffer rounding compromises, and therefore a
1000 UPM is too small because it forces too many such compromises.

Therefore 2000 is a good 'new VF standard', because 2000 is a simple 2x
conversion from existing fonts drawn on a 1000 UPM, and anyone who knows what
10 units can do for 1000 UPM will know what 20 units does too.

Additionally, values above 2048 would result in filesize increases with not
much added benefit.
  • 🍞 PASS Font em size is good (unitsPerEm = 2000).
🍞 PASS: Copyright field for this font on METADATA.pb matches all copyright notice entries on the name table ?
🍞 PASS: Check name table: FONT_SUBFAMILY_NAME entries.
🍞 PASS: Check name table: TYPOGRAPHIC_SUBFAMILY_NAME entries.
🍞 PASS: Length of copyright notice must not exceed 500 characters. 
--- Rationale ---

This is an arbitrary max length for the copyright notice field of the name
table. We simply don't want such notices to be too long. Typically such notices
are actually much shorter than this with a length of roughly 70 or 80
characters.
  • 🍞 PASS All copyright notice name entries on the 'name' table are shorter than 500 characters.
🍞 PASS: Familyname must be unique according to namecheck.fontdata.com 
--- Rationale ---

We need to check names are not already used, and today the best place to check
that is http://namecheck.fontdata.com
  • 🍞 PASS Font familyname seems to be unique.
🍞 PASS: Check a static ttf can be generated from a variable font. 
--- Rationale ---

Google Fonts may serve static fonts which have been generated from variable
fonts. This test will attempt to generate a static ttf using fontTool's varLib
mutator.

The target font will be the mean of each axis e.g:

**VF font axes**

- min weight, max weight = 400, 800
- min width, max width = 50, 100

**Target Instance**

- weight = 600
- width = 75
  • 🍞 PASS fontTools.varLib.mutator generated a static font instance
🍞 PASS: Check that variable fonts have an HVAR table. 
--- Rationale ---

Not having a HVAR table can lead to costly text-layout operations on some
platforms, which we want to avoid.

So, all variable fonts on the Google Fonts collection should have an HVAR with
valid values.

More info on the HVAR table can be found at:
https://docs.microsoft.com/en-us/typography/opentype/spec
/otvaroverview#variation-data-tables-and-miscellaneous-requirements
  • 🍞 PASS This variable font contains an HVAR table.
🍞 PASS: Font enables smart dropout control in "prep" table instructions? 
--- Rationale ---

This setup is meant to ensure consistent rendering quality for fonts across all
devices (with different rendering/hinting capabilities).

Below is the snippet of instructions we expect to see in the fonts:
B8 01 FF    PUSHW 0x01FF
85          SCANCTRL (unconditinally turn on
                      dropout control mode)
B0 04       PUSHB 0x04
8D          SCANTYPE (enable smart dropout control)

"Smart dropout control" means activating rules 1, 2 and 5:
Rule 1: If a pixel's center falls within the glyph outline,
        that pixel is turned on.
Rule 2: If a contour falls exactly on a pixel's center,
        that pixel is turned on.
Rule 5: If a scan line between two adjacent pixel centers
        (either vertical or horizontal) is intersected
        by both an on-Transition contour and an off-Transition
        contour and neither of the pixels was already turned on
        by rules 1 and 2, turn on the pixel which is closer to
        the midpoint between the on-Transition contour and
        off-Transition contour. This is "Smart" dropout control.

For more detailed info (such as other rules not enabled in this snippet),
please refer to the TrueType Instruction Set documentation.
  • 🍞 PASS 'prep' table contains instructions enabling smart dropout control.
🍞 PASS: There must not be VTT Talk sources in the font. 
--- Rationale ---

The goal here is to reduce filesizes and improve pageloading when dealing with
webfonts.

The VTT Talk sources are not necessary at runtime and endup being just dead
weight when left embedded in the font binaries. The sources should be kept on
the project files but stripped out when building release binaries.
  • 🍞 PASS There are no tables with VTT Talk sources embedded in the font.
🍞 PASS: Are there unwanted Apple tables? 
--- Rationale ---

Apple's TrueType reference manual [1] describes SFNT tables not in the
Microsoft OpenType specification [2] and these can sometimes sneak into final
release files, but Google Fonts should only have OpenType tables.

[1] https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6.html
[2] https://docs.microsoft.com/en-us/typography/opentype/spec/
  • 🍞 PASS There are no unwanted AAT tables.
🍞 PASS: All name entries referenced by fvar instances exist on the name table? 
--- Rationale ---

The purpose of this check is to make sure that all name entries referenced by
variable font instances do exist in the name table.
  • 🍞 PASS OK
🍞 PASS: A variable font must have named instances. 
--- Rationale ---

Named instances must be present in all variable fonts in order not to frustrate
the users' typical expectations of a traditional static font workflow.
  • 🍞 PASS OK
🍞 PASS: Variable font weight coordinates must be multiples of 100. 
--- Rationale ---

The named instances on the weight axis of a variable font must have coordinates
that are multiples of 100 on the design space.
  • 🍞 PASS OK
🍞 PASS: Name table entries should not contain line-breaks. 
--- Rationale ---

There are some entries on the name table that may include more than one line of
text. The Google Fonts team, though, prefers to keep the name table entries
short and simple without line breaks.

For instance, some designers like to include the full text of a font license in
the "copyright notice" entry, but for the GFonts collection this entry should
only mention year, author and other basic info in a manner enforced by
com.google.fonts/check/font_copyright
  • 🍞 PASS Name table entries are all single-line (no line-breaks found).
🍞 PASS: A static fonts directory with at least two fonts must accompany variable fonts 
--- Rationale ---

Variable font family directories kept in the google/fonts git repo must include
a static/ subdir containing static fonts.
These files are meant to be served for users that still lack support for
variable fonts in their web browsers.
  • 🍞 PASS OK
🍞 PASS: A font repository should not include fontbakery report files 
--- Rationale ---

A FontBakery report is ephemeral and so should be used for posting issues on a
bug-tracker instead of being hosted in the font project repository.
  • 🍞 PASS OK
🍞 PASS: A font repository should not include ZIP files 
--- Rationale ---

Sometimes people check in ZIPs into their font project repositories. While we
accept the practice of checking in binaries, we believe that a ZIP is a step
too far ;)

Note: a source purist position is that only source files and build scripts
should be checked in.
  • 🍞 PASS OK
🍞 PASS: Check variable font instances have correct coordinate values
🍞 PASS: Check variable font instances have correct names
🍞 PASS: Ensure VFs do not contain opsz or ital axes. 
--- Rationale ---

The 'ital' axis is not supported yet in Google Chrome. The 'opsz' axis also has
patchy support.

For the time being, we need to ensure that VFs do not contain either of these
axes. Once browser support is better, we can deprecate this check.

For more info regarding ital and opsz browser support, see:
https://arrowtype.github.io/vf-slnt-test/
  • 🍞 PASS Looks good!
🍞 PASS: Name table records must not have trailing spaces.
🍞 PASS: Checking OS/2 usWinAscent & usWinDescent. 
--- Rationale ---

A font's winAscent and winDescent values should be greater than the head
table's yMax, abs(yMin) values. If they are less than these values, clipping
can occur on Windows platforms
(https://github.com/RedHatBrand/Overpass/issues/33).

If the font includes tall/deep writing systems such as Arabic or Devanagari,
the winAscent and winDescent can be greater than the yMax and abs(yMin) to
accommodate vowel marks.

When the win Metrics are significantly greater than the upm, the linespacing
can appear too loose. To counteract this, enabling the OS/2 fsSelection bit 7
(Use_Typo_Metrics), will force Windows to use the OS/2 typo values instead.
This means the font developer can control the linespacing with the typo values,
whilst avoiding clipping by setting the win values to values greater than the
yMax and abs(yMin).
  • 🍞 PASS OS/2 usWinAscent & usWinDescent values look good!
🍞 PASS: Checking OS/2 Metrics match hhea Metrics. 
--- Rationale ---

When OS/2 and hhea vertical metrics match, the same linespacing results on
macOS, GNU+Linux and Windows. Unfortunately as of 2018, Google Fonts has
released many fonts with vertical metrics that don't match in this way. When we
fix this issue in these existing families, we will create a visible change in
line/paragraph layout for either Windows or macOS users, which will upset some
of them.

But we have a duty to fix broken stuff, and inconsistent paragraph layout is
unacceptably broken when it is possible to avoid it.

If users complain and prefer the old broken version, they have the freedom to
take care of their own situation.
  • 🍞 PASS OS/2.sTypoAscender/Descender values match hhea.ascent/descent.
🍞 PASS: Checking with ftxvalidator.
🍞 PASS: Checking with ots-sanitize.
🍞 PASS: Font contains .notdef as first glyph? 
--- Rationale ---

The OpenType specification v1.8.2 recommends that the first glyph is the
.notdef glyph without a codepoint assigned and with a drawing.

https://docs.microsoft.com/en-us/typography/opentype/spec
/recom#glyph-0-the-notdef-glyph

Pre-v1.8, it was recommended that a font should also contain a .null, CR and
space glyph. This might have been relevant for applications on MacOS 9.
  • 🍞 PASS Font contains the .notdef glyph as the first glyph, it does not have a Unicode value assigned and contains a drawing.
🍞 PASS: Font contains glyphs for whitespace characters?
🍞 PASS: Font has **proper** whitespace glyph names?
🍞 PASS: Whitespace glyphs have ink?
🍞 PASS: Are there unwanted tables? 
--- Rationale ---

Some font editors store source data in their own SFNT tables, and these can
sometimes sneak into final release files, which should only have OpenType spec
tables.
  • 🍞 PASS There are no unwanted tables.
🍞 PASS: Check correctness of STAT table strings 
--- Rationale ---

On the STAT table, the "Italic" keyword must not be used on AxisValues for
variation axes other than 'ital'.
  • 🍞 PASS Looks good!
🍞 PASS: Glyph names are all valid? 
--- Rationale ---

Microsoft's recommendations for OpenType Fonts states the following:

'NOTE: The PostScript glyph name must be no longer than 31 characters, include
only uppercase or lowercase English letters, European digits, the period or the
underscore, i.e. from the set [A-Za-z0-9_.] and should start with a letter,
except the special glyph name ".notdef" which starts with a period.'

https://docs.microsoft.com/en-us/typography/opentype/spec/recom#post-table


In practice, though, particularly in modern environments, glyph names can be as
long as 63 characters.
According to the "Adobe Glyph List Specification" available at:

https://github.com/adobe-type-tools/agl-specification
  • 🍞 PASS Glyph names are all valid.
🍞 PASS: Font contains unique glyph names? 
--- Rationale ---

Duplicate glyph names prevent font installation on Mac OS X.
  • 🍞 PASS Font contains unique glyph names.
🍞 PASS: Checking with fontTools.ttx
🍞 PASS: Each font in set of sibling families must have the same set of vertical metrics values. 
--- Rationale ---

We may want all fonts within a super-family (all sibling families) to have the
same vertical metrics so their line spacing is consistent across the
super-family.

This is an experimental extended version of
com.google.fonts/check/superfamily/vertical_metrics and for now it will only
result in WARNs.
  • 🍞 PASS Vertical metrics are the same across the super-family.
🍞 PASS: Check all glyphs have codepoints assigned.
🍞 PASS: Checking unitsPerEm value is reasonable. 
--- Rationale ---

According to the OpenType spec:

The value of unitsPerEm at the head table must be a value between 16 and 16384.
Any value in this range is valid.

In fonts that have TrueType outlines, a power of 2 is recommended as this
allows performance optimizations in some rasterizers.

But 1000 is a commonly used value. And 2000 may become increasingly more common
on Variable Fonts.
  • 🍞 PASS The unitsPerEm value (2000) on the 'head' table is reasonable.
🍞 PASS: Checking font version fields (head and name table).
🍞 PASS: Check if OS/2 xAvgCharWidth is correct.
🍞 PASS: Check if OS/2 fsSelection matches head macStyle bold and italic bits. 
--- Rationale ---

The bold and italic bits in OS/2.fsSelection must match the bold and italic
bits in head.macStyle per the OpenType spec.
  • 🍞 PASS The OS/2.fsSelection and head.macStyle bold and italic settings match.
🍞 PASS: Check code page character ranges 
--- Rationale ---

At least some programs (such as Word and Sublime Text) under Windows 7 do not
recognize fonts unless code page bits are properly set on the ulCodePageRange1
(and/or ulCodePageRange2) fields of the OS/2 table.

More specifically, the fonts are selectable in the font menu, but whichever
Windows API these applications use considers them unsuitable for any character
set, so anything set in these fonts is rendered with a fallback font of Arial.

This check currently does not identify which code pages should be set.
Auto-detecting coverage is not trivial since the OpenType specification leaves
the interpretation of whether a given code page is "functional" or not open to
the font developer to decide.

So here we simply detect as a FAIL when a given font has no code page declared
at all.
  • 🍞 PASS At least one code page is defined.
🍞 PASS: Font has correct post table version? 
--- Rationale ---

Apple recommends against using 'post' table format 3 under most circumstances,
as it can create problems with some printer drivers and PDF documents. The
savings in disk space usually does not justify the potential loss in
functionality.
Source:
https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6post.html

The CFF2 table does not contain glyph names, so variable OTFs should be allowed
to use post table version 2.

This check expects:
- Version 2 for TTF or OTF CFF2 Variable fonts
- Version 3 for OTF
  • 🍞 PASS Font has post table version 2.
🍞 PASS: Check name table for empty records. 
--- Rationale ---

Check the name table for empty records, as this can cause problems in Adobe
apps.
  • 🍞 PASS No empty name table records found.
🍞 PASS: Description strings in the name table must not contain copyright info.
🍞 PASS: Checking correctness of monospaced metadata. 
--- Rationale ---

There are various metadata in the OpenType spec to specify if a font is
monospaced or not. If the font is not truly monospaced, then no monospaced
metadata should be set (as sometimes they mistakenly are...)

Requirements for monospace fonts:

* post.isFixedPitch - "Set to 0 if the font is proportionally spaced, non-zero
if the font is not proportionally spaced (monospaced)"
  www.microsoft.com/typography/otspec/post.htm

* hhea.advanceWidthMax must be correct, meaning no glyph's width value is
greater.
  www.microsoft.com/typography/otspec/hhea.htm

* OS/2.panose.bProportion must be set to 9 (monospace). Spec says: "The PANOSE
definition contains ten digits each of which currently describes up to sixteen
variations. Windows uses bFamilyType, bSerifStyle and bProportion in the font
mapper to determine family type. It also uses bProportion to determine if the
font is monospaced."
  www.microsoft.com/typography/otspec/os2.htm#pan
  monotypecom-test.monotype.de/services/pan2

* OS/2.xAvgCharWidth must be set accurately.
  "OS/2.xAvgCharWidth is used when rendering monospaced fonts, at least by
Windows GDI"
  http://typedrawers.com/discussion/comment/15397/#Comment_15397

Also we should report an error for glyphs not of average width.

Please also note:
Thomas Phinney told us that a few years ago (as of December 2019), if you gave
a font a monospace flag in Panose, Microsoft Word would ignore the actual
advance widths and treat it as monospaced. Source:
https://typedrawers.com/discussion/comment/45140/#Comment_45140
  • 🍞 PASS Font is not monospaced and all related metadata look good. [code: good]
🍞 PASS: Does full font name begin with the font family name?
🍞 PASS: Font follows the family naming recommendations?
🍞 PASS: Name table ID 6 (PostScript name) must be consistent across platforms. 
--- Rationale ---

The PostScript name entries in the font's 'name' table should be consistent
across platforms.

This is the TTF/CFF2 equivalent of the CFF 'postscript_name_cff_vs_name' check.
  • 🍞 PASS Entries in the "name" table for ID 6 (PostScript name) are consistent.
🍞 PASS: Does the number of glyphs in the loca table match the maxp table?
🍞 PASS: Checking Vertical Metric Linegaps.
🍞 PASS: MaxAdvanceWidth is consistent with values in the Hmtx and Hhea tables?
🍞 PASS: Does the font have a DSIG table? 
--- Rationale ---

Microsoft Office 2013 and below products expect fonts to have a digital
signature declared in a DSIG table in order to implement OpenType features. The
EOL date for Microsoft Office 2013 products is 4/11/2023. This issue does not
impact Microsoft Office 2016 and above products. 

This checks verifies that this signature is available in the font.

A fake signature is enough to address this issue. If needed, a dummy table can
be added to the font with the `gftools fix-dsig` script available at
https://github.com/googlefonts/gftools

Reference: https://github.com/googlefonts/fontbakery/issues/1845
  • 🍞 PASS Digital Signature (DSIG) exists.
🍞 PASS: Space and non-breaking space have the same width?
🍞 PASS: Check mark characters are in GDEF mark glyph class) 
--- Rationale ---

Glyphs in the GDEF mark glyph class should be non-spacing.
Spacing glyphs in the GDEF mark glyph class may have incorrect anchor
positioning that was only intended for building composite glyphs during design.
  • 🍞 PASS Font does not has spacing glyphs in the GDEF mark glyph class.
🍞 PASS: Check mark characters are in GDEF mark glyph class 
--- Rationale ---

Mark characters should be in the GDEF mark glyph class.
  • 🍞 PASS Font does not have mark characters not in the GDEF mark glyph class.
🍞 PASS: Check GDEF mark glyph class doesn't have characters that are not marks) 
--- Rationale ---

Glyphs in the GDEF mark glyph class become non-spacing and may be repositioned
if they have mark anchors.
Only combining mark glyphs should be in that class. Any non-mark glyph must not
be in that class, in particular spacing glyphs.
  • 🍞 PASS Font does not have non-mark characters in the GDEF mark glyph class.
🍞 PASS: Does GPOS table have kerning information?
🍞 PASS: Is there a "kern" table declared in the font? 
--- Rationale ---

Even though all fonts should have their kerning implemented in the GPOS table,
there may be kerning info at the kern table as well.

Some applications such as MS PowerPoint require kerning info on the kern table.
More specifically, they require a format 0 kern subtable from a kern table
version 0, which is the only one that Windows understands (and which is also
the simplest and more limited of all the kern subtables).

Google Fonts ingests fonts made for download and use on desktops, and does all
web font optimizations in the serving pipeline (using libre libraries that
anyone can replicate.)

Ideally, TTFs intended for desktop users (and thus the ones intended for Google
Fonts) should have both KERN and GPOS tables.

Given all of the above, we currently treat kerning on a v0 kern table as a
good-to-have (but optional) feature.
  • 🍞 PASS Font does not declare an optional "kern" table.
🍞 PASS: Is there any unused data at the end of the glyf table?
🍞 PASS: Check for points out of bounds.
🍞 PASS: Check glyphs do not have duplicate components which have the same x,y coordinates. 
--- Rationale ---

There has been cases in which fonts had faulty double quote marks, with each of
them containing two single quote marks as components with the same x, y
coordinates which makes them visually look like single quote marks.

This check ensures that glyphs do not contain duplicate components which have
the same x,y coordinates.
  • 🍞 PASS Glyphs do not contain duplicate components which have the same x,y coordinates.
🍞 PASS: The variable font 'wght' (Weight) axis coordinate must be 400 on the 'Regular' instance. 
--- Rationale ---

According to the Open-Type spec's registered design-variation tag 'wght'
available at
https://docs.microsoft.com/en-gb/typography/opentype/spec/dvaraxistag_wght

If a variable font has a 'wght' (Weight) axis, then the coordinate of its
'Regular' instance is required to be 400.
  • 🍞 PASS Regular:wght is 400.
🍞 PASS: The variable font 'wdth' (Width) axis coordinate must be 100 on the 'Regular' instance. 
--- Rationale ---

According to the Open-Type spec's registered design-variation tag 'wdth'
available at
https://docs.microsoft.com/en-gb/typography/opentype/spec/dvaraxistag_wdth

If a variable font has a 'wdth' (Width) axis, then the coordinate of its
'Regular' instance is required to be 100.
  • 🍞 PASS Regular:wdth is 100.
🍞 PASS: The variable font 'wght' (Weight) axis coordinate must be 700 on the 'Bold' instance. 
--- Rationale ---

The Open-Type spec's registered design-variation tag 'wght' available at
https://docs.microsoft.com/en-gb/typography/opentype/spec/dvaraxistag_wght does
not specify a required value for the 'Bold' instance of a variable font.

But Dave Crossland suggested that we should enforce a required value of 700 in
this case.
  • 🍞 PASS Bold:wght is 700.
🍞 PASS: The variable font 'wght' (Weight) axis coordinate must be within spec range of 1 to 1000 on all instances. 
--- Rationale ---

According to the Open-Type spec's registered design-variation tag 'wght'
available at
https://docs.microsoft.com/en-gb/typography/opentype/spec/dvaraxistag_wght

On the 'wght' (Weight) axis, the valid coordinate range is 1-1000.
  • 🍞 PASS OK
🍞 PASS: The variable font 'wdth' (Weight) axis coordinate must be within spec range of 1 to 1000 on all instances. 
--- Rationale ---

According to the Open-Type spec's registered design-variation tag 'wdth'
available at
https://docs.microsoft.com/en-gb/typography/opentype/spec/dvaraxistag_wdth

On the 'wdth' (Width) axis, the valid coordinate range is 1-1000
  • 🍞 PASS OK

Summary

💔 ERROR 🔥 FAIL ⚠ WARN 💤 SKIP ℹ INFO 🍞 PASS 🔎 DEBUG
1 1 3 33 9 128 0
1% 1% 2% 19% 5% 73% 0%