A puppy picket pattern mixes tall spears with short ones: one tall spear every third or fourth position, with short spears between them. The short spears stop at or just above the top rail, so the run keeps the tall spears' rhythm while the infill reads lower and lighter.
The pattern is set by how often a spear is tall and how far the short ones rise above the rail (zero means they stop at the rail). Short spears can carry the same tip as the tall ones or be left plain. An alternating pattern is the simplest case: every second spear is short.
On the cutting list the tall and short spears are separate rows, each with its own cut length and quantity.