AC.ID

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.

On the rest of this site, I 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.

SYS.AC.ID

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

AC.ID+SUB

When we extend the end the notation is extended to AC.ID+SUB -- Area Category Sub-ID.