It appears that users of Jboss 7 will be often modifying these configuration files as they fine tune their server and when they discover how to implement new features.
It seems quite surprising to me that these files do not have the schema references identified in the file header. Any good XML editor would use those references to validate changes and new entries and thereby avoid a great deal of frustration for users and those who provide support for forum issues.
I realise that if jboss validated each xml file when starting up there would be performance penalty that may be unacceptable to many users. A command-line switch could be used to either turn on xml validation (if the default were that no validation is performed) or conversely to turn off xml validation if the default state was that xml validation was on.
Personally I favor having a switch that turns off validation - to be used on production servers only.
If the schema/dtd files were published online and referenced within the configuration xml files, future changes to the schema structure would be "enforced" upon the user community as they attempted to use an out-of-date version when upgrading to a new version of JBoss AS 7.