http://www.metal-archives.com/content/rules

As of the 2015-09-15 update, exceptional entries (side-project, or scene-significant nonmetal tracks) are now officially off-limits for normal users. The rules have not been updated as of now, as it still states that the submission of normal users are [simply] discouraged upon submitting such entries.

This is what the written rules state, according to Azmodes and on the Homepage:

In any case, as a consequence of this higher level of scrutiny (and the ongoing clean-up), we have decided that the addition of exceptions of any kind is to be restricted to staffers-only, so that we can better manage and gauge (and contain) this ancillary, delicate part of the database.

So again, while the written rules have described it as "discouraged [for regular users]" for a long time already, submission of non-metal side-projects or other potential exceptions is now 100% off-limits for non-staff. Metal only, please. Side-project submissions have been comparably rare, but they do trickle in and in order to save time and effort for both users and mods please desist from submitting them.

It will be fully updated soon enough... Derigin is still working on a new version of the rules.

Yeah, unfortunately I've taken a little longer than usual getting around to this. Apologies for that. Who knew trying to clean-up the rules would take time?