VTA and SRA?

Read it again.

SRA = the angle formed between:
1) a vertical line through the lowest contact point of the stylus and
2) the line of the stylus's contact ridge or edge.

#1 never changes, but #2 can be changed in several ways.

The stylus's contact edge can be tilted forward or back by altering the height of the tonearm. It also changes as a side-effect of any alteration in downforce (VTF). Your own tonearm (listed as a Graham Phantom Supreme) has these adjustments.

You also change SRA (inadvertently) virtually every time you change LP's, since different LP's have different thicknesses.

Dougdeacon,so if I change the SRA by adjusting the height of the tonearm the VTA is not changed?

Both would be changed.

Changing SRA without simultaneously changing VTA would require altering the angle between the stylus and cantilever... not recommended. ;-)

If the ideal VTA is 20 degrees off the horizontal, then I assume the ideal SRA is 20 degrees off the vertical, correct?

1-2 degrees, not 20 degrees.