What metadata schemes are there for the description of linguistic resources?

Quite a few. Examples are: Dublin Core, Open Language Archives Community
See: http://www.language-archives.org

read more

(which is an enriched version of Dublin Core), ISLE Meta Data Initiative
See: http://en.wikipedia.org/wiki/IMDI

read more

, the Text Encoding Initiative
See: http://en.wikipedia.org/wiki/Text_Encoding_Initiative

read more

header.