An instruction (command) initiates an action on the calculator. For example, ClrDraw is an instruction to the calculator to clear drawn elements from a graph. Instructions cannot be used in expressions. In general, the first letter of each instruction name is uppercase. Some instructions take more than one argument, as indicated by an open parenthesis at the end of the name. For example, on the TI-84 Plus CE online calculator, Circle( requires three arguments, and has two optional arguments:
Circle(X,Y,radius[,color,linestyle])