What about 00-09?

You may be wondering why we started our areas at 10-19 and not 00-09, and our categories at 11 rather than 10.

We reserve these for the system

Sometimes you want to keep information about the system, in the system. I call this ‘Management & Meta’.

Meta basically means ‘self-referential’. It’s about itself. Get it? If not, don’t stress.

00-09 is about the system itself

I always reserve these numbers for a special area called 00-09 Management & Meta. Inevitably I want to store some information in my Johnny.Decimal system about my Johnny.Decimal system. That goes here.

For example, I have to save text notes in a folder on my disk. That folder has to live somewhere, and it lives in a category in 00-09.

One of the text notes I keep at work serves as a quick-reference index to my Johnny.Decimal system. It’s called 00.00 Index.

10, 20, 30 … 90 are about those categories

In the example we’ve been using, 20-29 was Administration but our first category was 21 Company registration. What happened to 20?

We reserve these numbers for ‘management & meta’ information about the category. Although I hardly ever use them, it’s rare that I have more than nine categories in an area. I don’t miss the wasted number, but I always appreciate it when I need it.

Confused? Don’t worry

If you want to use the zeros, use them. It doesn’t matter.