Freeze the checklist on some statuses

You may want to freeze the definition of the checklist on some statuses.  I.e. when Work Item is Approved, do not apply the template of the checklist, but use the checklist that was defined so far.

You can setup this using Configuration Properties: 

nextedy.checklist._TYPEID._FIELDID._STATUS.mergeTemplate
nextedy.checklist._TYPEID._FIELDID.mergeTemplateResolved

so when you apply this on checklist "dod" and status "reviewed":

nextedy.checklist.dod.reviewed.mergeTemplate=false
nextedy.checklist.dod.mergeTemplateResolved=false

Initialise Checklist

Please note, that the checklist must be initialised, i.e. once the checklist is frozen, it shows the data that has been stored so far. This means that if you add some new checklist items, but you do not touch the checklist status, the checklist will still not have the data stored in Work item.

You can ensure that the checklist template was applied (synchronized into work item) prior you marked you item as "approved" (or any other workflow status) via workflow function.

Example:

Configure the workflow function "Mark Approved" so it runs the workflow function "ChecklistApplyTemplate", as a result the system will ensure the checklist is Synchronized to the latest version of a template, when running this wf function.

1. Add a workflow function
   
2. Set function parameter "checklist" to comma separated list of checklist custom fields.
   

Make the checklist readonly

In addition to that you can also make the custom field "definition of done"/dod readonly using the readonly fields or using the Polarion field based permissions.