Gettext/Editable-Message-Catalogs

From Get docs

16.2.1 Editable Message Catalogs

These file formats can be used with all of the msg* tools and with the xgettext program.

If you just want to convert among these formats, you can use the msgcat program (with the appropriate option) or the xgettext program.

PO:    PO - Portable Object
Java .properties:    Java .properties
GNUstep .strings:    NeXTstep/GNUstep .strings