Add clarification in description to note that due to lack of scope attribute for any col header, incomplete header/id reference in secondary header row creates inability to compute header (for the secondary header).
Also update test case results for failure of 12.1-4 to denote which specific cell fails.
Add clarification in description to note that due to lack of scope attribute for any col header, incomplete header/id reference in secondary header row creates inability to compute header (for the secondary header).
Also update test case results for failure of 12.1-4 to denote which specific cell fails.