a keyword that defines the variables belonging to each patch
a keyword that takes a plural name and a singular name as input and defines a class of turtles with that name
a keyword that takes one or more variable names as input and defines a new global (cross-program) variable with each name
a keyword that defines the variables belonging to each turtle or breed of turtles
a reporter that reports the set of all turtles
keywords that begin and end procedures
a command that advances the tick counter by one and updates all the plots
a command that makes the agent exit immediately from the enclosing procedure or command