Frameless Shower Installation

[leevis]

Hi All
I've purchased a shower which is frameless and I need some help in working out how to install the thing.
I have the instructions and there is a W1 and a W2
W1 is the width between the wall and the outside of the upright channel that the glass goes into.
W2 is the width between the walll and what's looks like some kind of clip which goes on the end of the glass to connect to the door.
The issue is that W1 is 852-872 and W2 is 860-880
The upright has a bit of movement on it ie its not just a hole, it has some lateral.
My query is about the amount of variation there, 20mm is quite a bit and I am guessing that the door won't fit if these are wrong.
What should I aim for?

 

[leevis]

Attached is the diagram which is confusing me, I can't work out whether its saying that the outer extremity of the upright is 872 (W1 for 900) or I just have to put is so that the outer extremity is somewhere between 852 and 872. It's the same on both uprights, I just need to work out exactly what this means. My brain is saying that if I fix these at different distances (lets say one at 862 and one at 852) the door surely isn't going to fit?

 

[leevis]

I've been looking at this again, the width of the track that goes vertical is 20mm. Could it be that when it says 852-872 could this mean that is the exact distance it needs to be ie start at 852 and end at 872?