A question regarding the M600 parameters E, U, and L

### Did you test the latest `bugfix-2.1.x` code? N\A ### Question I want to configure M600 on the fly in a UM Cura post-processor. I am looking for a clarification regarding whether the E, U and L parameters should be entered as positive or negative values. The information I've found appears to be contradictory. The M600 command parameters `E`, `U`, `L` are listed on the [Gcodes page](https://marlinfw.org/docs/gcode/M600.html) as requiring negative values. It seems odd that the `L` (load filament) parameter would also require a negative value. - "`[E<pos>]` | Retract before moving to change position (**negative**, default `PAUSE_PARK_RETRACT_LENGTH`)" - "`[U<pos>]` | Amount of retraction for unload (**negative**)" - "`[L<pos>]` | Load length, longer for bowden (**negative**)" It appears that configured like this: `M600 B1 E-6.5 U-450 R205 T0 L-30 X0 Y0 Z2` there will be an E movement of -6.5mm (retraction), an unload of -450mm, and a reload of -30mm?? These are from `M600.cpp`: * `E[distance]` - Retract the filament this far * `U[distance]` - Retract distance for removal (manual reload) * `L[distance]` - Extrude distance for insertion (manual reload) Those make it seem like they should all 3 should be positive values. Then later in M600.cpp these appear to be switching the +/- signs: * `-ABS(parser.axisunitsval('E', E_AXIS, PAUSE_PARK_RETRACT_LENGTH))` * `-ABS(parser.axisunitsval('U', E_AXIS, fc_settings[active_extruder].unload_length)) : 0.5f;` * `ABS(parser.axisunitsval('L', E_AXIS, fc_settings[active_extruder].load_length))` That appears that they are a mix and get changed later...or something. If someone could take a moment to clarify the proper input for "Retract, Unload, and Load" I'd be much obliged. GregValiant