You are correct - 1600 x 1024 is missing from the page to which you linked
And Silicon Graphics who sold monitors at this resolution say that 1600 x 1024 is a VESA standard and Apple's 22" Cinema Display also uses 1600 x 1024. It has certainly been supported by VESA before
Anyway, the above is besides the point
I have attached the EDID timing parameters file in TXT format to this message
Does this file provide all the information needed?
What has to happen for your software to support 1600 x 1024?
Best wishes
Nigel