Each input title is processed in turn, and is ignored if it does not denote a [[data tiddler|DataTiddlers]]. The sorted list of property names is retrieved from the data tiddler and then [[dominantly appended|Dominant Append]] to the operator's output.
Note that behind the scenes, the name/value pairs in a dictionary tiddler are represented as a [[JSON object|JSONTiddlers]]. JSON objects do not maintain a guaranteed ordering and so we cannot reliably retain the ordering of the data in the file.
Where the content of a tiddler is in JSON format with an array as its root, the <<.op indexes>> operator retrieves a selection of integer indices instead.