AC.ID notation

As we have seen, the number before the decimal tells us what area and category we're in. The number after the decimal is the ID.

I often use AC.ID notation as shorthand to refer to any generic Johnny.Decimal system. A, C, and ID serve as variables.

For example:

  • AC.ID is any ID in the system.

  • 1C.ID is any ID in area 10-19.

  • 11.ID is any ID in category 11.

  • AC.11 is ID .11 in any category.

See this in action on the first two figures of the standard zeros page.

SYS.AC.ID

When we use multiple systems the notation is extended to SYS.AC.ID ā€“ System Area Category ID.