User exit u31ad returns the current port number.
u31ad code.number
| code.number | When following the user exit, the code number specifies where the value is to be placed. | |
| a | Outputs to the alternative output buffer. | |
| p | Outputs to the primary input buffer. | |
| s | Outputs to the current output buffer. | |
| t | Outputs to the terminal. | |