[pmwiki-users] allow my markup only on certain pages? (include context)

[Anno]

Put the markup in local/Groupname.YourPage.php file instead 
local/config.php, and it will be active only with Group.YourPage.

Alternatively only for one particular group:
local/Groupname.php

Explained here:
http://www.pmwiki.org/wiki/PmWiki/PerGroupCustomizations