A rule template is stored as an asset, a "prototype" for a rule based on an existing DSL.
This is coupled with the Guided Editor GUI in the BRMS - when a template is built, a user can lock it so that only "fields" (text boxes) can be edited. Or, then can choose to allow specified DSL items to be added in specified positions in the rule (but other items are left). Some fields may also be locked.
When a user creates a rule - they can choose a template to base it on - and then can only change certain values from then on.