1USR and 1US (annunciator)
HP48: 1USRAnnunciator for single-key User Mode. When this annunciator is shown, the User Keyboard will be active for the next keystroke only, and then user mode will automatically be turned off.
When system flag -61 is clear (default), pressing the USER key (called USR on the HP48S) turns on 1USR mode, and pressing it a second time locks USER mode on. If you find yourself usually pressing USER twice instead of just once, set flag
-61; this makes the USER key toggle USER mode off and on with one keystroke, eliminating the need to ever press it twice (and eliminating 1USR from ever appearing).
See also: USER ASN