Windows NT Print Manager and Custom Form Limitations

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Background

There are three components to each printer driver: the base driver, the user interface (UI) driver, and the characterization data file. The characterization data file is a PPD file for PostScript devices, a PCD file for plotting devices, or a minidriver for raster devices. It describes the physical characteristics of one or more print devices (including the name, dimensions, and margins of each predefined form that the print device supports), and the maximum and minimum length and width of custom-defined forms. The forms database on a Windows NT computer initially contains a wide variety of forms. When you install printer drivers, the spooler checks the characterization data file and adds the driver's forms to the Windows NT forms database.

In Windows NT, each form associates a name with a set of length and width measurements, and margin measurements. For example, the Letter default form is 8.5" wide by 11" long, and has 0" margins. Only the form name must be unique. Different print devices often recognize different names for the same physical form dimensions, so the forms database often has several forms that have the same dimensions, the same margins, or both.

When you run Print Manager and define a printer's form-to-tray mapping, or its default form, Print Manager queries the driver for the physical sizes of the forms the print device supports. Print Manager then displays a list including every form in its database that has the same physical size as any of the forms predefined in the driver. Consequently, these lists often show multiple forms with identical sizes, such as Letter and Letter Small. Additionally, you can't choose large page sizes such as Tabloid (11" by 17") on print devices that cannot support such sizes.

Problem

In some cases, the maximum length or width of a custom form is smaller than the length or width of the print device's largest predefined form. For example, the published specifications for the Epson LQ-870 ESC/P2 print device state that the maximum physical page width is 10.1", and that the imagable width is only 8.0". When using the Letter form, this print device enforces .5" of combined left and right margins, so that applications will not attempt to print on more than 8.0" of the page.



The Windows NT printer drivers for such print devices reflect these specifications. For example, you could define a custom form 8.5" wide and 7.0" tall with 0" combined right and left margins, but this would have an imagable width of 8.5". Because this would conflict with the device's specification, Print Manager will not let you use this form on this device. As a result, all custom-sized forms that you want to use with this device under Windows NT must have a physical width less than or equal to 8.0" even though the device supports physical pages up to 10.1" wide.

NOTE: The Epson LQ-870 ESC/P2 described in this example is not necessarily the only print device with which you can encounter this problem.

To identify these restrictions:

1. Run Windows NT Write.
2. Select a printer.
3. Select a predefined page size (such as Letter).
4. Select the Page Layout option from the Document menu, and enter 0" for all margins.
5. Select OK.

If the print device does not allow 0" margins, Write returns an error message showing the minimum required margins for this form and print device. For example, if you select an Epson LQ-870 ESC/P2 printer, choose the Letter form, and request 0" left and right margins, the error message reports that the minimum left and right margins are each .25".

The maximum printable width is:

   (physical width of Letter form) - (minimum left margin) - (minimum
   right margin)
				

Using the Epson LQ-870 ESC/P2 as an example, the formula is 8.5 - .25 - .25, which equals 8.0.