I need to identify a list of AIX command strings that can be used to parse Powerbroker logs for changes that are being made by Unix SysAdmins. Need to filter out (as much as possible) inquiry or routine maintenance activity and concentrate on software/security changes.

This is for internal SOX monitoring (control self-assessment) - I am not an auditor.

Can anyone help? Suggestions?

You can grep -v the file to exclude data. For instance --

cat mylogfile | grep -v "routine"
or
cat mylogfile | grep -v "routine" >mylogfile.2

The first example will send the file to stdout (your screen normally) while the second example will direct the output to a new file. In both cases, any lines with the word "routine" would be excluded.
You could try the second approach, and then if you find another keyword to exclude re-do the command but with the next keyword, for example

cat mylogfile.2 | grep -v "ordinary" >mylogfile.3

Be aware of overall filespace, and remember to clean-up when done. Sometimes log files are very large. Perhaps this gives you a start?