In the ooRexx Refence book (rexxref.pdf) there is a chapter titled The Builtin Classes. Within that chapter there is a section titled "The Windows Specific Classes"
This section should be moved for several reasons. First off, most of those classes are not builtin. Second, the ooRexx Reference book is generic reference, describing the classes, methods, functions, BIFS, syntax, etc., of the interpreter on all platforms. Third, the Windows specific classes are all extensions, which, if they were documented in their own book, would be documented in the same manner as the other extensions, like rxmath, rxftp, rxsock, etc..