We need to make it very clear that the parition keys refer to push like runlist attributes such as RunIndex and not post imposed attributes.
Also the actual triggering page need not be present on the sheet. (insert sheets with no content but triggered by the first / last / 42nd page.
SheetActivation SHALL specify the conditions under which an optional sheet SHALL be produced.
The condition element defines the condition when a CellCondition, PageActivation, PageCondition or SheetActivation is active when processing
a layout with @Automated="true".
The source of the Part elements that SHALL be evaluated by Condition SHALL be the input RunList of the Imposition process.
The content pages of the RunList that are evaluated by Condition NEED NOT be present on the Layout that is currently being evaluated. For instance a job summary will not contain anycontent pages but will typically be triggered by the last content page of a job.