Building Wheels

I did all my calculations and have my worksheet ready to plug in the numbers into spokecalc. For some reason there is a brand new box asking for “width between holes”.

I googled and i read and couldnt find a clear answer on what number to put there.

WHAT IS THE “WIDTH BETWEEN HOLES”?

I have “Alex Adventure 2 Rim – 26", Rim, Black/Silver, 36H” rims.