Raphael,
you are correct the tool numbers seem to come from the sequences they were extracted from. Not exactly sure when it started but I don't like it!! It's something else to check before coding a cl file other wise you have tool numbers scattered all through the tool carosel.
Seems when adding tools to your program using templates you could have tools 1 through 4 set then a template will throw in a tool 15 then when you add another tool it will be too16 because it wont go back to tool 5 and put it there.
Steve