Looks like a welded wire fabric spec. If it is, the first number indicates the spacing of the wire (in); the second number indicates the size of the cross-sectional area within the wire (in x .01).
But I can't see using WWF as the grating to hold GAC, so check with structural grating manufacturers. The nomenclature may (or may not) be the same.
Remember: The Chinese ideogram for “crisis” is comprised of the characters for “danger” and “opportunity.”
-Steve