What do the letters in Festool product names mean?

What do FEQ or REBQ Plus mean?

Here' some shortcut explanation:
  • R - relaunch, new version
  • E - electronics, variable speed
  • B - safety break
  • Q - plug it cable
  • FS - with guide rail
  • FSK - with cross guide rail
  • Plus - in a systainer
  • EC - brushless motor