I can see no way to be able to determine which Special page references are defined by the JSPWiki.properties with the pattern jspwiki.specialPage.*, like the [{$interwikilinks}] variable publishes interwiki links defined in JSPWiki.properties.

While the value of a specific special page, e.g. jspwiki.specialPage.Login, may be read as a wiki variable, there is no way to determine which Special page references are defined.

None of these WikiMarkup will return the specialPage values:

jspwiki.specialPage.* = [{$jspwiki.specialPage.*}]

jspwiki.specialPage = [{$jspwiki.specialPage}]

I suggest that one of the above forms may be used to return a list of all values that are "specializations" of the jspwiki.specialPage property. The value should be returned as a comma separated list of PageName=URL.

Care should be taken to not bypass general security by allowing protected property values to be read in this way.

If this feature is implemented, I furthermore suggest to add this property to the SystemInfo page.