Function harmony

[ratata]

Hi

I'm new here, so first a short presentation: My name is Jonathan, I'm 19 years old and from Denmark.

I have a question about function harmony. What is the name for the chord on the seventh step. Here are some examples:
(T=tonic, S=subdominant, Tp=tonic parallel, M_=Submediant)

Green Day - American Idiot (verse):
Ab...Db...Gb-Db....Ab
T....S....?--S.....T

The Pipettes - Dirty Mind (chorus):
C....Bb...Am....Ab
T....?....Tp....M_

Blur - Girls And Boys:
G....C....F....Eb
T....S....?....M_

I hope someone can I answer my question.

[ratata]

don't bother answering. i have figured it out. it can be interpreted in a number of ways, e.g. subdominants subdominant, although it's not really suitable to do so in many situations.