Entity

Use the e:[entitytype] parameter to list one or more entity types that were affected by an action.

Supports multiple (comma separated)!

e:cow will query activities that affected cows.

See Entity Types 

Also see etag.

Negation

As of Prism 4.4, this parameter allows negation. Negating an action will exclude results. It is important to note that unlike Prism 3, the syntax has the exclamation point before the colon. You cannot use a negated parameter with its normal equivalent.

Example: /pr l e!:cow (Queries all entities except "cow")