I have a fairly simple requirement, but it's not clear to me how to implement it.
A`term from a certain vocabulary will appear in each user's profile. A forum or forum container may have a term from the same vocabulary. For users with a certain role, I want to deny access to forums that have a different term.
For example, suppose the vocabulary terms correspond to colors. For users with role X and the term Blue, I want to allow access to forums that have the term Blue or no term, and deny access to others. For users with role X and the term Chartreuse, I want to allow access to forums that have the term Chartreuse or no term, and deny access to others. And so on. For users with roles other than X, all forums should be accessible — even though these users may also have color terms in their profiles.
“Deny access” should mean not only that the user cannot read or post to forums, but that they aren't visible at all.
I did some research in the Drupal.org forums and found a suggestion that the Taxonomy Access module be used for a similar purpose, but it's not available for Drupal 6. It's not clear to me whether that implies that the capability is built into the Drupal 6 Taxonomy module. It's also not clear whether this module would do exactly what I want.
I can implement this capability myself if I have to, but I'd rather use existing code if it can be made to do what I want.
If I will have to do my own implementation, I'll welcome suggestions on how to approach the problem.