When the SPLOT program is started, it is in the state corresponding with the state of the simulated plotter just switched on. When coming to plotting a new file, the program performs only the change paper operation. In this case the program (plotter) is in the state in which it has been left by the commands of the previous file. That is why it is generally recommended to place an initiating command sequence to the beginning of each file. It will bring the plotter to the well known state. Otherwise it can happen that the same file can be drawn in another way every time, dependently of the contents of the previous plotted files. The author recommends to use the initiating sequence IN;RO;IP;IW; (in some plotters the IN command does not influence the setting of rotation). For HP-GL/2 plotters you should also include the BP (begin plot) instruction before the IN instruction.
In other cases the program is brought to the state corresponding with the switching off and on (i.e. resetting) the plotter in these cases: