Charge input
A special move that needs you to hold a direction for a while, then press the opposite — hold back, press forward, and the projectile is out.
Guile's Sonic Boom in Street Fighter II is the textbook case: hold back for roughly a second, then press forward and punch. The engine counts the frames the "charge" direction has been held; let go for too long or miss the window and the counter resets. Unlike motion inputs, which are sequences, this is built on holding.
The design effect is to reward grounded, patient play — holding back is the same as blocking, so charge characters play defensively by sheer mechanics and can't just throw the move out on a whim. "Charge partitioning" is the advanced trick of banking charge during other animations and spending it later.