When a building a vertical table in webi

Thank you in advance for you time!

When I put together a small table of 3 variables in a vertical table the result was two rows of data. The first row was like so:

Restraints Alternatives Orders

xxxxxxx 8 1

null 8 1

It appears to have created a sum row? Or there is a null in my data but I don't see the null?

Do the tables automatically create a summary at the bottom if the objects are measures?

Thanks Scott

ps what is the purpose of the "primary tag" below?