function PerformNamedAction(const ActionName: string): Boolean;
| ActionName | string. Name of the action, as written in the document. The four standard navigation names are NextPage, PrevPage, FirstPage, and LastPage. |
| Result | Boolean. True when the action was recognised and carried out, False for an empty name, an inactive document, or a name with no library-supplied meaning. |
Named actions (ISO 32000-1 12.6.4.11) are how a document asks the viewer to do something rather than describing it itself. An OpenAction or a form button can raise one, and this executes it
The four navigation names move PageNumber. Movement is clamped rather than wrapped: a document asking for NextPage on the last page stays put instead of jumping back to the first
Anything else is document-defined and returns False, so a caller can tell "did nothing" from "moved". To take the standard names over as well, handle OnNamedAction