Mimicing $_GET['main_page']

[retched]

Right, so if you're after so-called human-friendly-URLs, then the suggestion by mc12345678 is the best place to start.

But if you're wanting to get into writing custom code for very specialized use, then probably adding something to extra_functions to do your work would be a good starting point.
Then:
- see if $_GET['ufs_card'] is set
- if it is, then take its value and do whatever lookups are relevant, and then set $_GET['main_page'] and any other $_GET vars required to trick the site into doing what you requested (ie: rebuilding the URL by setting GET params)

This more or less points me in the right direction, I knew it was somewhere in extra_functions but didn't know the starting point. My only other question would be if there is an innate function in ZenCart that builds the URL (?main_page=index&......) or is this going to need to be built by me?