A couple of locales have DefaultNarrowName defined for months:
Estonian (currently only in master):
The narrow name corresponds to MMMMM in date formats.
When using a date format containing the narrow version of the month name, this is not preserved after saving & re-opening the document:
- In Calc, the MMMMM gets replaced with MMM when saving as .ods (ODF 1.2 extended). Curiously enough it's saved/loaded correctly to/from .xlsx (2007-365).
- When using date field in e.g. Writer and setting it to one of the MMMMM dates, it also gets replaced with MMM code when saving as .odt. When saving to (or loading from?) .docx, the month part is completely lost.
Same behaviour with 6.4.4 and current master. Behaviour is (easily) testable only starting from 6.2 when narrow month names became usable with Hungarian locale.
@László: this might be interesting for you, too.