Allow empty 031N $6 and don't include an entry in the validation log

[hemmefelix]

Hi @nichtich ,

currently the schema validation will add an entry in the log when validating PICA+ plain records where 031N $6 is empty.

picadata validate -f plain -s k10plus-2025-06-19.json econis_2025-06-01_2/econis_2025-06-01_23.txt
192411254X: PICA subfield $6 must be non-empty string

This subfield is not required to contain a value given the K10+ rules, see https://format.k10plus.de/k10plushelp.pl?cmd=kat&val=4024&katalog=Standard#$6 and the examples section:

4024 $v1$b2005$6

An empty $6 indicates that the journal is still current and has not yet ceased publication. Here the full PICA+ record: https://unapi.k10plus.de/?id=k10plus:ppn:192411254X&format=pp

When validating records with picadata, an empty 031N $6 should not be considered a metadata issue and therefore should not create an log entry.

Cheers! Felix

[nichtich]

PICA::Data wrongly assumes subfields must not be empty. There is a validation option allow_empty_subfields but it cannot by passed by the command line client yet (by the way the command line client should support a subset of validation options supported in avram-js). The assumption should better be removed. If subfields must not be empty, this can better be expressed within the schema.