"MEsa" transistor...what is it?

[petemoore]

  Cleaning up a huge pile of scrap boards, I ran across these 2SA471 transistors...they looked Ge like, so I looked them up on the NTE site.
  It crosses to the NTE126, high speed switching PNP.
  But it says "Mesa", I know about gain 'n leakage, just I looked up 'mesa transistor' and figure you know what these are and would spare a few words about what the 'mesa' part means.
  They came from a console Radio/Amp Frame I used to make my tube amp on.

[petemoore]

http://smithsonianchips.si.edu/augarten/p12.htm
  This explains it was an early method of transistor production.
  I'll test 'em out in a FF or two.
  I'm in the middle, start at the beginning and read [cool read BTW] by scrolling to the bottom of the page and clicking on 1.