I use the HTML attribute <tag … title="text_to_appear" … frequently in any HTML I author by hand (or where a forum tool menu provides a field, as this one does). In most browsers, it causes a tooltip popup to appear showing the text_to_appear (aka hovertip).
I was lately wondering if FM can generate that for cross-references and other hypertext, to it's various output workflows, in particular PDF. It appears that the answer presently is: no, and no.
Apparent No#1: Unstructured FM's insert-Xref dialog has no fields for anything but target ID and format. The inset-hypertext has no fields for anything but command ID and target address. There are fields for some other object types, like hotspots in images.
Apparent No#2: Even if FM could routinely support 'title' in hypertext (which would likely be useful for HTML/XML workflow), it appears that PDF has no standard construct for it (perhaps because Postscript didn't either). When people ask for PDF in-document tooltips on various fora, various hacks are suggested, such as scripts & forms.
Acrobat Pro has a right-click Edit Link which shows some metadata on the Actions tab, such as (for an FM generated PDF xref): Destination name: M2.9.12345.Paratag.Text
These questions are in support of a potential enhancement request, but I'd like first to make sure I grasp the whole current, if not historical context of this.
A present project is already doing a hack for spot cross references, and if FM supported 'title', I'd have used it to note the target of every one.