I'm working on a custom taxon plugin and I'm making use of wp_set_post_terms().
If I'm not mistaken, with the fourth parameter ($append) left off, it should completely replace any taxons (meaning any that aren't in the array I pass are removed), correct?
I'm doing something like this:
$terms = array('a','b','c'); wp_set_post_terms($post_id, $terms, 'my_taxon');
It's working, partially. Say it had the terms a, b, c, d, afterwards it'd still have a, b, c, d (when it should have removed the d.