When a driver is initialized, its tags are set to default values that are determined by the driver. Tag values can be changed by the application at any time, and the application can save tag values so that they can later be restored. In this way, an application can save and restore current settings, a set of named settings, and/or its own start-up settings. Note however that a driver's default settings cannot be changed by an application with one exception: user-settable defaults.
The one exception to default settings being made by the application is a mechanism for setting driver defaults that are critical or at least important to the operation of a driver. For example, many scanner drivers let the user configure and save the default paper size, default SCSI address, or default interface I/O address. The actual values vary depending on the selected scanner, and many scanners have no user-settable defaults. Any tags other than those presented by the driver when it is selected are hard-coded to factory default settings.
The toolkit has functions for setting tags back to their default values, for finding a tag's default values, and for finding the current value of a tag.
More information on tags can be found in Work with Tags section.