Applications pass null-terminated strings to atom tables and receive string atoms (32-bit integers) in return. String atoms have the following properties:

• The maximum number of string atoms allowed is 16K. The values of string atoms are from 0xC000 through 0xFFFF.

• The maximum amount of data that an atom table can store is 60K. This includes the control data that the operating system uses to manage the atom table (32 bytes for the table plus 8 bytes for each string atom).

• The maximum length of an atom name is 255 characters. A zero-length string is not a valid atom name.

• Case is significant when searching for an atom name in an atom table, and the entire string must match. No substring matching is performed.

• A usage count is associated with each atom name. The count is incremented each time the atom name is added to the table and decremented each time the atom name is deleted from the table. This allows different users of the same string atom to avoid destroying each other's atom names. When the usage count for an atom name equals zero, the system removes the atom and atom name from the table.