I have a upvc door with hinges the same as the one in the diagram from
the bottom of following page:-

http://www.upvcdoorcompany.co.uk/guarantee.htm

The 3 hinges in total both have 2 allen key adjustments.

My question:-

I presume the key at the bottom of the hinge adjustments the height of
the door, please correct me if I'm wrong, but what does the key on the
side do? (Position A)

Any help would be greatly appreciated.