Compare named filter run prefix :filter with filter Operator which applies a subfilter to every input title, removing the titles that return an empty result from the subfilter
Tip
Compare named filter run prefix :reduce with reduce Operator which is used to used to flatten a list of items down to a single item by repeatedly applying a subfilter
Tip
Within the filter runs prefixed with :reduce, :sort, :map and :filter, the currentTiddler variable is set to the title of the tiddler being processed. The value of currentTiddler outside the subfilter is available in the variable ..currentTiddlerIntroduced in v5.2.0