Before any actual plotting calls are made, a graphics program must call plinit, is the main initialization routine for PLplot. It sets up all internal data structures necessary for plotting and initializes the output device driver. If the output device has not already been specified when plinit is called, a list of valid output devices is given and the user is prompted for a choice. Either the device number or a device keyword is accepted.

There are several routines affecting the initialization that must be called before plinit, if they are used. The function plsdev allows you to set the device explicitly. The function plsetopt allows you to set any command-line option internally in your code. The function plssub may be called to divide the output device plotting area into several subpages of equal size, each of which can be used separately.

One advances to the next page (or screen) via pladv. If subpages are used, this can be used to advance to the next subpage or to a particular subpage.