IBM 4230 User Guide - Page 202

When a test is not running, pressing Return or Cancel Print tells the printer to exit test mode and perform a partial reset. If you press Return, the printer goes to online not ready; if you press Cancel Print, the printer goes to online ready. Pressing Enter or Start begins a test. Some of the tests print and then exit back to the Operator Print Tests menu automatically, while other tests require you to give input using the operator panel keys to complete the test. See the individual test descriptions on the following pages for specific instructions. While a test is running, pressing Stop or Cancel Print halts the test. If you press Stop, the display returns to the Operator Print Tests menu. If you press Cancel Print, the printer exits test mode, performs a partial reset, and becomes online ready. 5-2 User's Guide