Enigma rotors - numbered or lettered ??

Mark Baldwin <mark-znuCwvN0N+Nhyzs96duibmhr/[email protected]> Fri, 22 Jun 2012 10:09:47 +0100

Newsgroups	gmane.science.cryptography.bletchley-park
Message-ID	<001101cd5056$c63c69f0$0202a8c0@DJ8FQB2J>

Can anyone explain, please, why the index rings on some Enigma rotors 
are lettered A - Z, whereas others are numbered 1 - 26?

Cryptographically there is no significance, and the A-Z/1-26 conversion table 
is printed on the standard instruction sheet usually attached to the inside of the lid.

Thanks!
Mark Baldwin