Originally posted by griphon2
As for IV chords. I prefer to look at them as sub-tonics, rather than subdominant. It's just a preference. Once you add or imply a tritone, it's dominant.

Ok. The dominant in a chordal structure of a key structure has a different meaning than the dominant chord itself. In the chordal structure, dominant just means 5th degree above the tonic. Well you know what a dominant chord is, ex. dom7 dom9.

This is clear because the 5th degree above the minor (key)tonic is still reffered to as dominant. And the 4th below is subdominant. Even though those chords are not dominant chords. Confusing yes but true.