First, remember, these can't be "reserved" only "preferred". Second, I recommend that you use number of 1,000 or higher, ask suggested bt CIYAM and myself earlier. This is so that these IDs can be resevered and used in a more-official sense in the future.
My .02 cents on it. You can do whst you want to do, but after working in IT and with communications for years, I can say that "cherry picking" lower IDs (which is how this could be perceived) is a little unprofessional.
Please understand, I'm not hassling you, but trying to educate/advise on the situation and explain why I don't support using those values.
Okay, I agree.

I've got no problem with that.. So we're reserving lower 1000 IDs (from 1 to 1000) for core use???
Then I think I'll take 1001 to 1100 then (I'll need to revise my app, but thankfully, I haven't really uploaded too many transactions yet).. IF there is no objection.. Thanks for the feedback, btw.. Really appreciate it!
PS: Just re-read your statement, I understand where you're coming from, but I think we should definitely set up a reservation system and strictly enforces it for the reason outlined above -- Let's say if a developer doesn't check data format and just process data blindly, it will break an application and lead to bad user experience, don't you agree?

(And I think it will happen very often)
BTW - thanks for playing the advisor role, definitely appreciate it!