Shimano numbering/series

wings988
wings988 Posts: 106
edited March 2009 in MTB general
A question regarding the Shimano numbering system and ranges. It seems obvious by the design of their website the hierarchy of their product ranges but I'm not sure where the non series range fits.
Is the Non Series range considered as the lower end of what they offer?
I'm slightly confused as they obviously do the cheaper ranges such as Alivio where for instance the crankset is numbered M410 but they do a "non series" crank M542 and the Deore is M532. Does the higher number mean its higher spec? and why not fit into a series?

:?