...since someone else opening a new thread just to list open spots will fall off the front page quickly.
You misunderstood the proposal I am making. I did not suggest to create a brand new thread mentioning open slots for signature campaigns.
I was suggesting adding which slots are open in the subject line of that particular signature campaign.
Similar to the example which I quoted in OP.
What I think the best to do here is to standardize the ranks by tiers/category like (1) for Legendary/hero member, (2) for Sr. Member, (3) for full member, (4) for member and Jr. Member.
or we can use the Alphabet A,B,C.
That would still lead to additional confusions. For example it might be logical to you that Legendary is #1, others will say shouldn't Newbies be #1 (smallest number) and Legendaries the biggest number. Going from the lowest to the highest rank instead of vice versa. Additionally, you would need to separate the Legendary and Hero ranks as some campaigns pay more for Legendaries despite the fact that both ranks use the same signature.
But now I don't know good alternative to replace it.
It's enough to say that it's FULL. The reason why it's full doesn't matter.