"Put on hold or released" seems more like the type of activity that should be in the Logging tab of the object's Report window. If the object's report doesn't have a Logging tab (or doesn't show the info you want), you should also check the parent's report as well. (Pretty easy from Statistics with "Statistics Activator.")
For example, if I set a breakpoint, the log is on the parent workflow's report, NOT on the job's report:
2014-07-23 11:32:03 - U0011520 Runtime modification: User 'JSCHMIDT/CORP' set a breakpoint at task 'V3_MSGCTR_PUBLISH' (RunID: '0093113013').
And if I set a recurring task to STOP, the log is on the recurring task's report, not on the job under it:
2014-07-23 11:33:12 - U0011103 Task 'LOGIC_ONLY' ('0093148550') was stopped by user 'JSCHMIDT/CORP'.
If a job didn't run because the schedule was stopped, check the schedule's log:
2014-07-23 11:38:22 - U0011103 Task 'TIM_SCHEDULE' ('0093149410') was stopped by user 'JSCHMIDT/CORP'.
Modifications like this on an activated Job/Workflow
are documented in the Workflow Report (Protocol Tab). If the Job in question is still
activated, right click on the Job and choose "Last
Report". You should find all the information in there.
Modifications like this on Job properties of a
Workflow (not activated / the object itself) are documented in the
Documentation Tab of the Workflow. By comparing the "OLD" Workflow versions,
you can determine who changed what.
inside a whole client are documented in the revision logs.
Some amount of this type of information is also available from the System Overview, Messages option. The displayed messages can also be exported to a CSV file.
I assume that the source of these messages is kept in some file or a table that could be read directly. I further assume that there is some system setting that controls their retention but I don't deal with this as part of my regular job duties.
I'm a bit confused. Are you trying to determine what changes were made to a Schedule object via an Edit or modification of a task's status via the Activities Monitor during execution?
Here's the link to the documentation on it.
Retrieving data ...