Count attribute (K')

The count attribute applies only to macro instruction operands, to SET symbols, and to the system variable symbols. It has a numeric value equal to the number of characters:

That constitute the macro instruction operand, or
That are required to represent as a character string the current value of the SET symbol or the system variable symbol.

Notes:

The count attribute reference can be used only in arithmetic expressions.
The count attribute of an omitted macro instruction operand has a value of 0.
Doubled quotes ('') in quoted character strings count as one character. Doubled ampersands (&&) in quoted character strings count as two characters. For more information about character pairs see Evaluation of character expressions.
These pairing rules mean that the length attribute of a character variable substituted into a character constant might be different from the count attribute of the substituted variable.
The count attribute differs from the Number (N') attribute, described below.