Each input title is processed in turn, and is ignored if it does not denote a [[data tiddler|DataTiddlers]]. The list of property names is retrieved from the data tiddler (in no particular order) and then [[dominantly appended|Dominant Append]] to the operator's output.
Where a tiddler's [[content is JSON|JSONTiddlers]] with an array as its root, the <<.op indexes>> operator retrieves a selection of integer indices instead.