http://www.oasis-open.org/committees/tc_home.php?wg_abbrev=office#technical
If you download
OpenDocument v1.0 Relax-NG Schema and take a look into it, you will find that it has about 18,000 lines in the one file.
http://www.ecma-international.org/news/TC45_current_work/TC45-2006-50.htm
If I donwload
Ecma TC45 OOXML Standard Schemas - Draft 1.3 and take a look into it, it seems to me that their schema is well divided and organized.
What do you think?