basically, a peice of equipment that has various functions that can be used to aid you in building. these may include:
a calculator
draft box (to measure an area for various things)
notes
help forum
and more!
the draft box may still seem silly to you, but:
if you are doing a building job that has different size requirements or whatnot, heres what you can do:
use the draft box to measure a building area, and thus, calculate the cost