What does [ANN] mean?

[nsajko]

Previously discussed here:

What's the deal with that "[ANN]" stuff in titles in Package announcements?

I guess it stands for (package) ANNouncement? Although, the first time I saw it I thought it referred to a lady named Ann… What is the purpose of putting it in a thread’s title? I see that not all package announcement threads have it. When I make my own packages, should I put [ANN] in the title of the announcement thread?