Confusion regarding the Shimano numering system I have learned that the first couple of letters on a stamped Shimano part mean the part type e.g. FD - front derailleur, and the first digit indicates the series e.g.

M960 XTR/DCL 9s
M950 XTR 9s
M900 XTR 8s
M800 Saint 9s
M760 DeoreXT/DCL 9s
M750 DeoreXT 9s
M740 DeoreXT 8s
M700 DeoreXT 7s
M630 DeoreDX 7s
M580 DeoreLX/DCL 9s
M570 DeoreLX 9s
M560 DeoreLX 8s
M550 DeoreLX 7s
M520 Deore 9s
M510 Deore 8s


However, when I look at a couple of bikes, there is nothing similar:


FC-M191 is an Alivio crank arm, while the "1" should have indicated a Tourney
ST-EK70 and SL-M310 - those are both shifters, the first one with integrated brake lever. Why are the first two letters different? What is "EK"?
CS-HG30-8I - cogset marking - wtf!?


Ideally, I would appreciate a .pdf Shimano catalogue, the paper version of hich I have seen at the LBS. Alternatively, explaination about my listed parts would also be an answer.
Not a full answer, but I can fill in one small blank for you - in the CS-HG30-8I, the HG refers to Hyper Glide - this is Shimano's name for multi-speed sprockets that are designed to allow smooth gear shifting.