Many Pilot pens had a letter on the cap, that I assume denoted a line which the pen belonged to... some designs seem to cross over a fair ammount, for example I have seen "Super" pens that were very similar to "E" pens, which in turn shared many design cues with "V" pens from a similar time period. Then again, I have pens from the same line *and approximate time period* with different colored caps?!?

Was E the predecessor to the Elite line? If so, was there a "C" line that predated the Custom pens?

Does anybody know how consistent the features or cosmetics were within these lines, or what actually made an "E" an "E" and so on?