I have registered extra taxonomies (on top of tags and categories) such as people and places. These work fine, and I have customised my index.php to use get_query_vars to show the correct posts when a URL like
is accessed. What I need to know is where does wordpress get the functionality from to select posts by /tag/tag1 or /tag/tag1+tag2 etc? I can't see how the core code knows to select the tags from the URL.
I would ultimately like to copy the functionality for an arbitrary number of taxonomies such as /people/person1+person2 or /places/place1 and have the standard loop get the correct posts, just as it does for a URL with /tag in it.
Any pointers to info would be really appreciated...