In the following example, the 0 tells the CLIST to expect no positional parameters. (If there are no positional parameters, a zero is required.) The notation STATE(NY) gives the variable STATE the default value of NY.

PROC 0 STATE(NY)

The invoker can override the default value by passing the keyword parameter with another value, for example:

EX clistname 'STATE(NJ)'

or

%clistname STATE(NJ)

Then the variable STATE takes the value NJ.

If you want a variable to have no default value but allow invokers to specify a value, use empty parentheses. The following PROC statement lets invokers pass keyword parameters such as STATE(NY) or STATE(NJ).

PROC 0 STATE()

In the example above, if an invoker passes the keyword parameter STATE without a value, the CLIST prompts for the value. If a invoker does not pass the keyword STATE at all, the variable STATE takes a null value.