Deciphering the set inventory element IDs

For the past several years, the instruction books for LEGO sets have included inventories of the parts (not including extras). The element IDs are longer than the ones we've all seen molded inside parts, which are used on Peeron and BrickLink. Mike M. asserted that part of the code denotes the color but it doesn't seem that simple. (It was a quick, fragmentary assertion so I may have missed something). Perhaps his LUGBULK Bag Labels project will help clarify.

Hypothesis:
* 6-digit IDs: 4-digit element, 2-digit color.
* 7-digit IDs: 2-digit color, 5-digit element.
* There may be several synonymous color codes. (Different plastics?)

For example, in Space Police 5970 Freeze Ray Frenzy, the black elements have the following codes (sorted and punctuated according to my hypothetical decomposition):

* 45-52531 torso, 45-52671 legs, 45-22653 helmet, 45-62148, 45-50642 tanks, 45-29173 fin, 45-52413 jet nacelle, 45-47765, 45-38722.
* 42-23247 robot arm.
* 2447-26 visor, 4733-26 brick, 4081-26, 2555-26, 2412-26 grille, 3021-26 3x2 plate, 3957-26.

But the dark bley elements have these codes:
* 45-51179 legs, 45-51188 torso, 45-40386 cheese grater.
* 42-10848 1x1 tile, 42-61908 handlebars, 42-10698 bullhorn, 42-11119 jumper, 42-10660, 42-11051 binocs.

So the prefixes "45" and "42" are being used both for black and dark bley. The hypothesis is further demolished by the set's white elements: 30-6901, 41-43254, 41-16816, 42-49112.