03 Aug, 2009, Kline wrote in the 1st comment:
Votes: 0
This is the discussion thread for mobile_building
11 May, 2010, David Haley wrote in the 2nd comment:
Votes: 0
This thread was recently tagged with "m-class" – what does that mean?
11 May, 2010, quixadhal wrote in the 3rd comment:
Votes: 0
Maybe it's about building on m-class planets?

That's my guess… I didn't tag it. :)