Pedigree Forge allows entering dates using the French Republican Calendar, in use from 1793 to 1805. Years are numbered from 1 to 14 (1793 to 1805), and the months have different names. For example:
4 Vend 1 FR
Would be 4 Vendemiarie in Year 1.
11 Nivo 14
Would be 11 Nivose, in Year 14.
The recognised moths abbreviations are: Vend, Brum, Frim, Nivo, Pluv, Vent, Germ, Flor, Prai, Mess, Ther, Fruc, Comp.
The FR is optional, French Republican dates can be recognised by the month names.
Technical Note: French Republican Calendar dates are imported/exported to GEDCOM with the @#DFRENCH R@ (FRENCH_R in version 7).