Is there a simple way to determine what subfield of a field is actually displayed in the GUI

[sarah kreisler]

A user sees "project", "link", and "summary" but behind the scenes, the user is usually setting a subfield.  how can a developer determine which subfield is being changed.

For example:

when linking two issues, a user is setting the issuelinks-in/outwardIssue-key sub-field

when selecting a project the user is setting the project-name sub-field 

when typing in the summary, the user is setting the summary field

[Alexey Matveev]

You can develop a listener. In the listener you have access to what was changed for the issue. You can use the getChangeLog method of the IssueEvent class. You can find more info here:

https://docs.atlassian.com/software/jira/docs/api/7.0.5/com/atlassian/jira/event/issue/IssueEvent.html

[sarah kreisler]

I am trying to do a monthly audit and need to determine a minimal set of field names (and sub field names) to pull, I am not trying to monitor every action and don't have continuous access to the jira instance.

There has to be a table somewhere in the jira code that defines this information, I shouldn't have to sniff packets and guess

[Nic Brough -Adaptavist-]

"sub-field" doesn't mean anything in Jira terms, so I'm slightly hazy on what you mean by it.  Issues have fields, that's it really.

Alexey has defined the best answer for you already - find or write a listener that can capture the data you want at the time things change.  If that's not going to work for you, then use the REST API to get data about fields changing.