Generally, in electronics, "DC component" is defined as the average
value (say, over a period of a periodic waveform). So a 1V peak sine
wave sitting on top of 1VDC would have DC component of 1.0V.
A 1V peak sine wave has a DC component of 0.

The RMS value is the heating value- a 1 ohm resistor with 1VDC across
it will dissipate 1W. A 1 ohm resistor with 1.414V peak sine wave
across it (1 V RMS) will dissipate 1W.

A 1 ohm resistor powered with a 1V peak sine wave sitting on top of
1VDC will dissipate a bit more than 1 watt (RMS value is sqrt(3/2) if
you want to get analytical about it, so about 1.22W).

Thank you SP. Amid all the chest-pounding and playground antics here I can
actually learn something.