<p>I know that <code>M73 P19</code> means "Set completion progress to 19%", and I suspect that <code>M73 R42</code> means "Set remaining time to 42 minutes", but what is <code>M73 Q17 S43</code>? I can't find description of such syntax.</p>

<p>The command is seen in <code>.gcode</code> files produced by PrusaSlicer.</p>

The tooltip for "Supports remaining times" under
```
Printer Settings -> General -> Firmware
```
in PrusaSlicer quotes:
```
```
Emit M73 P[percent printed] R[remaining time in minutes] at 1 minute intervals
into the G-code to let the firmware show accurate remaining time.
As of now only the Prusa i3 MK3 firmware recognizes M73.
Also the i3 MK3 firmware supports M73 Qxx Sxx for the silent mode.
```
```
Therefore:
P = Percentage printed, normal mode
R = Remaining time, normal mode
Q = Percentage printed, silent mode
S = Remaining time, silent mode