spec css3 writing modes sideways left

text-orientation: sideways-left and sideways in CSS Writing Modes Level 3

Background

1. sideways-left is not implemented yet

• sideways-left is for Latin and other non-East Asian vertical flow, while other values (mixed, upright, sideways-right) are important values for East Asian vertical flow.

2. sideways has dependency on sideways-left, and thus is implemented differently from the spec by 3 implementations (AH, Blink, WebKit)

• Mongolians must use sideways-right, not sideways, but the 3 implementations allow both.

Proposals

sideways-left

1. Keep as is
2. Mark at risk and put a note for attention not to implement the sideways value if you don't implement this value
3. Defer to Level 4

sideways

1. Keep as is
2. Mark at risk and put a note for attention not to implement this value differently from the spec
3. Change the spec to follow the interoperable 3 implementations (same behavior as sideways-right)
4. Defer to Level 4

Notes

1. www-style thread
2. Concerns of the value could prevent the property from being implemented because of its complexity.
3. IIUC, design concerns were raised 2-3 times before at F2F and offline, though I could not find them in the minutes.
4. IE is the only UA that supports the use case (though using the writing-mode properly, not the text-orientation property.)
5. EPUB 3 CSS Profile refers to this property.