Question : undocumented traces

why are some traces not mentioned in the official doc:
http://technet.microsoft.com/en-us/library/ms188396%28SQL.90%29.aspx

example: Trace 3604

Thanks

Answer : undocumented traces

This trace flags were documented in SQL Server 6.5/2005+ versions in  Books Online, but was not documented in SQL Server 7.0 and SQL Server 2000..

http://www.mssqlcity.com/Articles/General/SQL2000TF.htm