base=, if not set, name of article ({{PAGENAME}}) is used.
stem=, if not set, base is used.
pluralstem=, if not set, stem is used.
genitive=, used to set the ending for genitiv, if not set, -s is used. Mostly used on nouns where the base form ends in -s to avoid duplicated, erronous -s. Just adding genitive= is sufficient to suppress the default -s.
definitions=, which of the definitions that the declension apply to, if not set valid for all definitions.