# Mixed two and three digit categories

**URL:** <https://forum.johnnydecimal.com/t/mixed-two-and-three-digit-categories/463>\
**Category:** Concepts\
**Created:** [May 12, 2022, 7:18pm UTC](https://forum.johnnydecimal.com/t/mixed-two-and-three-digit-categories/463 "2022-05-12T19:18:23Z")\
**Posts on this page:** 1\
**Showing post:** 3

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**Author:** ![johnnydecimal](https://forum.johnnydecimal.com/user_avatar/forum.johnnydecimal.com/johnnydecimal/32/1759_2.png) [@johnnydecimal](https://forum.johnnydecimal.com/u/johnnydecimal)\
**Post date:** [May 17, 2022, 9:31pm UTC](https://forum.johnnydecimal.com/t/mixed-two-and-three-digit-categories/463/3 "2022-05-17T21:31:23Z")

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Haha hey @Tommu319! Sorry I can be a little slow around here.

Yeah look, what we’ve learned from this forum over the last year or so is that if it works for you, it’s probably right. I had in my mind when I wrote the site these hard and fast rules, and it turns out they don’t work for everybody.

Here you have two quite distinct systems. It doesn’t feel like they’ll ever ‘meet’. In which case I’d say go for it. Your ‘personal’ system should just use the standard JD system with numbers from `10-19` through `90-99` (see [my personal system](https://forum.johnnydecimal.com/t/my-personal-system/412) for an overview of mine), then your work system does the same but with 3-digit project IDs at the front, as described [here](https://johnnydecimal.com/concepts/multiple-projects/).

I note that they won’t ‘meet’ because now you can keep whatever records separate and one system won’t be confused by another system’s different numbering. That keeps things clean.

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