| The W3C XML Schema group have always insisted that "Schemas" is
| the correct plural for W3C XML Schemas, not withstanding that
| "schemata" is appropriate for some other kinds of schema things in
| the universe.
I did an investigation of this right at the beginning of the XML
Schema effort and came to the same conclusion. There are some
people who insist on "schemata" (my friend Makoto Murata is one of
them), but "schemas" seems to have won the day.
My reasoning in preferring "schemas" is that while "schemata" is
more fun to say and affords an opportunity to demonstrate one's
literacy (or knowledge of Kantian philosophy, take your pick),
it's a rare construction in English -- the only parallel that
springs to mind is "stigmata" -- and the fate of words like
"indices" (now so misunderstood that one sometimes sees the
back-formation "indice") and "phenomena" (which many people seem
to believe is a singular noun) persuades me that we'd better stick
to something that follows the rules taught in introductory English
classes. Besides, it's shorter.
Jon