Use the %var_name or %parameter_number notation to define variables for parameter values. The number corresponds to the index of the parameter; parameters are indexed beginning with 1. Negative numbers index from the last parameter to the first.
Variables with names beginning with an underscore are reserved for special values. They generally have only one value. The table below describes the reserved variable names.
| Name | Description |
|---|---|
| _line, _col | Line and column numbers of the call in source code. |
| _file | Index of the file in the file table. |
| _uid | UID of the node of the call in the syntax tree. |
| _fail | A permanently undefined variable. Use it to cause explicit failure. |
| _yes | A non-empty string for use as a true value. |
| _no | An empty string for use as a false value. |
| _pgmname | Name of the calling program. |
| _hcid | HyperCode ID of the call node. |
| _varname nn | If parameter number nn is passed using a simple variable reference (not a constant or an expression), this substitution variable contains its name. Otherwise, it is undefined. |