The particle data commands are outlined in this chapter.

There needs to be at least one PARTICLE_SEED command. As many
PARTICLE_SEED commands as necessary are allowed. Each unique
PARTICLE_SEED command defines a distinct set of particles. A
USER_EQUATION_INITIAL_CONDITION command is allowed only for
pairings of particle seed groups and user equations. Each of the pairings defined by the
particle seed commands and the user equations specified by the
user_equations parameter in the EQUATION
command requires a corresponding USER_EQUATION_INITIAL_CONDITION
command. If no equations are specified by the user_equations
parameter in the EQUATION command, no
USER_EQUATION_INITIAL_CONDITION commands are needed.