What Relevant Data does SSMC=1 refer to in ACS 2013?

SSMC=1 shows ‘Same-sex married-couple household where not all relevant data shown as reported’

and

SSMC=2 shows 'All other same-sex married-couple households

But the description and code windows both do not explain what relevant data is not shown as reported. And I have no idea where to find what they mean… So any clarification is much appreciated.

Thanks in advance!

Respondents with an SSMCvalue of 1 were logically allocated as a same-sex married-couple, even though they were missing valid responses for SEXor RELATE. More information about the introduction of SSMC in the 2013 ACS can be found here.

I hope this helps!