The following are a few things that look like errors in the current schema-for-
schema posted on http://www.w3.org/2001/XMLSchema.xsd 

Some of them have been discussed here in the past or even mentioned in the 
errata, but don't seem to be reflected in the posted xsd.... They are all minor 
things, but they all do get in the way of actually using the schema-for-schema 
to validate schemas. Here is my list of changes: 

1. finalDefault needs to permit "list" and "union" 
2. the type of the <element> element in an <all> group needs to be given a name 
so that it is legal to use the type in both a base type and a restriction when 
using the allModel (otherwise it breaks one of the particle-valid (restriction) 
rules). 
3. The regular expressions that describe integrity constraint xpaths need to be 
modified to permit whitespaces in certain places, as discussed in one of the 
errata. 

See:
http://lists.w3.org/Archives/Public/www-xml-schema-comments/2003JulSep/0087.html