If someone is -6 cyl -1 astg = -7 Agreed ?
If someone is +6 cyl + 1 astg = +7 Agreed
Assuming you meant -6 SPH there?
CYL-inder is a measure of astigmatism itself.
I think 'taking into account' means that total correction, including SPH and CYL, cannot exceed 6D, therefore making the above prescription ineligable.
Not sure about the +/- thing, suppose it would depend on the method of the optician. I do know however, that whether it is +/-, it is irrelevant in calculating your overall correction from SPH and CYL.
Basically, add the numbers together. If your still not sure, phone GAtwick and read them your prescription...
Tamesy