bp
), which are equal to 1/72 of an inch. (You can actually
define the set of possible choices in the configuration
file).
You can ask Ipe to show the grid points by selecting the function grid visible from the misc menu. The same function turns it off again.
You request Ipe to snap to the nearest grid point by setting the button labeled + to on. Note that the +-sign resembles the orthogonal grid lattice.