ms/audit is a SAP Parameter attribute which is used to control Option to trace events into trace file information. This is available within R/3 SAP systems depending on the version and release level.
Below is the standard documentation available and a few details of the attributes values .
Depending on this parameter, additional information is written to the
trace file, also for trace level 1. The individual values can be totaled
to perform the actions simultaneously.
0 : No additional actions
1 : Logons and logoffs from application servers
2 : Application servers are removed from the select mask, or reinserted.
See SAP Parameter Documentation for full SAP documentation for this profile parameter.