This is part of the 1910 census image for Louis Demar and his household in Chicago, Illinois. In addition to the typical information, there are abbreviations written in an apparently different color of ink. Those abbreviations are clues as well and their meanings have been indicated on the image.
The "H" for Louis and "Wf" for Alfreda really do not provide any information that is not already on the census itself---they are listed as the "head" and "wife" respectively. However, there are abbreviations for Wm. Frame and Mary Frame that do provide additional information. The faint "NH" on Wm's line indicates that he is Not the Head of household, even though he is a married male living within the household. The "Wf" on the line for Mary indicates that she is married to the person on the line above her.
Of course, one might say that it looks pretty much like they are husband and wife anyway, but it's always nice to have a little more evidence in that direction.
