I came across a document that defines all these settings and wanted to share it here.
Regular (non-heated) hose
The DreamStation system has five humidity level settings with the following relative humidity set points:
0 = OFF
1 = 15% RH
2 = 65% RH
3 = 75% RH
4 = 82% RH
5 = 95% RH
Corresponding heater plate temperature set points:
0 = OFF
1 = 47C +/-3.5C
2 = 51C +/-3.5C
3 = 55C +/-3.5C
4 = 60C +/-3.5C
5 = 65C +/-3.5C
Heated Tube Humidification Mode
When heated tube is connected, the Fixed and Adaptive modes cannot be utilized.
Tube temperature set points:
0 = Heated tube is OFF (plate operation determined by humidity level setting)
1 = Starting Ambient Temperature +4 F +2.2C
2 = Starting Ambient Temperature +7 F +3.9C
3 = Starting Ambient Temperature +10 F +5.5C
4 = Starting Ambient Temperature +13 F +7.2C
5 = Starting Ambient Temperature +16 F (86F maximum) +8.8C (30C max)
Five humidity level settings with the following relative humidity set points:
0 = Heated plate is OFF (heated tube operation determined by heated tube temperature setting)
1 = 70% RH
2 = 74% RH
3 = 77% RH
4 = 81% RH
5 = 85% RH
RH = relative humidity