Without further ado, the following was found:

Issue:    I<x\\ -\\ n*y> → I<x>\\ -\\ I<n>*I<y>

"On success, these functions return the value I<x\\ -\\ n*y>, for some "
"integer I<n>, such that the returned value has the same sign as I<x> and a "
"magnitude less than the magnitude of I<y>."