Each input title is processed in turn, and is ignored if it does not denote a [[data tiddler|DataTiddlers]]. If the corresponding tiddler contains property <<.place P>>, and the value of this property is not empty, then its value is appended to the output.
<<.tip "Unlike most other [[Filter Operators]], the [[selection|Title Selection]] output by <<.op getindex>> can contain duplicates. To avoid duplicates, use `getindex[P]unique[]`.">>