In answer to midazolam\'s question about change ringing, it is indeed normal to start and finish with \"rounds\", but this cannot normally be achieved in such a short section, so I guess that finishing in rounds is more satisfying than starting there. Normally bells are given numbers, but I think the letters are the musical notes, so gfedc is part of the descending c major scale - called \"rounds\". If you listen to church bells, you should hear this pattern at the start and end of every piece of ringing. The lightest bell (g here) is called the treble, and normally follows a simpler pattern than the other bells. In this puzzle, it twice moves from first to last position and back again. Thus, each of the two column sections is a \"lead\". Normally, all leads would show the same pattern, but with the heavier bells permuted. Is suspect that this proved a bit difficult, so Aedites used two different patterns (or \"methods\").
I hope this hasn\'t bored you all (I\'ve tried to be brief!). However, I\'ve just finished my first ever words Listener (having done the number ones for ages) so I\'m feeling a bit chuffed.