Melodic augmented/diminished intervals and the compensating-step (recovery) rule

A melodic augmented 2nd and melodic augmented 4th/diminished 5th (the melodic tritone) are forbidden as direct melodic motion in species counterpoint and strongly discouraged generally. Separately, the 'compensating step' rule: any melodic leap larger than a third should be followed by stepwise motion in the OPPOSITE direction, filling in the leap and keeping the line's contour smooth.

A melodic line leaping a perfect 5th upward and CONTINUING upward by another leap rather than stepping back down — two leaps compounding in one direction with no recovery.

Fux/Jeppesen (species melodic rules).

This rule can be decided from pitches, durations and voices — no layout required. A validator can check it before anything is drawn.