So, yesterday Sky TV decided that BBC1 is no longer 169 and the Arts Channel is no longer 157 etc. etc. etc.
The numbers of channels in Sky's layout are not as opaque as wonks like my would prefer. And there sure ain't long lived as yesterday proved.
My guess is that the big re-org is to make way for all the scrumptious HDTV variants. They may also have been pressure on the semantic banding : 300 for movies. 400 for sport that sort of thing.
So here is the upshot: (1) embuing numbers with semantics (especially allocating ranges) will bite you one day. (2) If you don't embue numbers with semantics (such as allocating ranges) you are safe but don't have many customers because customers want identifiers to be less-than opaque.
Simple to use with an occasional earthquake renumbering beats harder to use with no earthquakes.