@ArMaTeC
Tags must be 3 to 5 letters only and must be composed of alpha numeric characters, letters must be capitals, also 4 or 5 letter tags must have an underscore following, 3 letter tags can also have the underscore but it is optional.
Whilst the tag you have requested is only 4 letters long there are a couple of things wrong with it.
1./ All letters must be in capitals as the text at top says.
2./ ARMA tag is already taken.
You no longer need to request tags in this topic, the first post clearly states that you can still use this topic to report problems using the new tag request interface.......available from the front page.
Use this interface to try and register a tag.
Planck