Plot settings are represented as AcDbPlotSettings objects, which are stored in several ways in an AcDbDatabase. One group of plot settings is stored with each layout in the database; these are the defaults that AutoCAD displays when a user edits layout properties in the AutoCAD Page Setup dialog box. Plot settings are also represented in an AcDbDatabase as named page setups that can be applied to override the plot settings stored in a layout.
Developers can create plot settings objects and use them as overrides when plotting layouts using the plot APIs. If you choose to do so, you must provide complete settings. In other words, the object must contain all the necessary information for plotting, and not just the desired overrides. To accomplish this, you can copy the plot settings from the layout and then change specific settings programmatically.
When a plot is initiated, an AcPlPlotInfo object is created. This object specifies which layout to plot and what settings to use. (The plot settings in the layout are used if the plot info object does not specify plot settings overrides.) A device override may also be applied by the user to make one-time changes, such as specifying double-sided copies or plotting to a DWF file.
Before plotting can begin, the AcPlPlotInfo object must be validated to ensure that the devices, media, plot style tables, and other plot specifications exist on the system and are available for the current plot. See the validate documentation for more information on specific checks that are performed during validation.