This is totally and completely unimportant, but I'm curious. Although some user-generated illustrations don't, almost all 12a*7 technical diagrams and data sheets put pin 1-2-3 in section 2 (or triode B) and pin 6-7-8 in section 1 (or triode A). I know (I think?) the two triodes are identical. Logical reason? Historical reason? or...?