I really like the way the RDB and VMS log error messages.
They are categorized with:
%<APP>-E-
%<APP>-W-
%<APP>-I-
For Error, Warning, and Informational level messages.
For example:
%DCL-I-SUPERSEDE, previous value of CNXSERVICE has been superseded
(DCL reports that an environmental variable has replaced an older value)
%RDB-W-META_WARN, metadata successfully updated with the reported
warning -RDMS-W-PRFCREATED, some users or roles were created
(A 'grant all' on table <table> to <user> causes RDB to warn that
users/roles were created)
%RDB-E-STREAM_EOF, attempt to fetch past end of record stream
(Cursor fetch on end of stream [one error that really isn't much of an
error])
It is especially nice when you are searching through a detailed log
file. You can look for all warnings/errors by searching for a percent
sign. You can search for error level messages by searching for a "-E-"
and that sort of thing.