Sending default characters in single-byte outline fonts

Because the Load Code Page Control (LCPC) IPDS command is used to download an outline code page to the printer, PSF can use this command to tell some printers to print the default character whenever a missing code point or missing character is encountered. For those printers that support this function, the default character for both single-byte and double-byte outline code pages is sent to the printer through the LCPC IPDS command.

Many printers do not support sending the default character to the printer with the LCPC IPDS command. For those printers, you can use the Send default character parameter in the Printer Inventory (see Send default character) or XTP7SDCH in Exit 7 (see XTP7SDCH) to request that PSF pass the default character information to the printer by fully populating the code page of an outline single-byte code page (this does not work for an outline double-byte code page). The Code Page Control (CPC) structured field in the code page identifies the ID of the character to use when no character is assigned to a code point. By fully populating the code page, any code points that are undefined are filled in with the default character information from the CPC structured field. If the code page is not fully populated, the printers use a space if an undefined code point is used in the data.

Unlike raster fonts, PSF cannot verify that the default character selected is actually in the character set. Therefore, it is up to the user to ensure that the default character selected is actually in the character set. The printer uses a space as the default character if a code point calls out a character that does not exist in the font character set.

The Send default character parameter in the Printer Inventory or XTP7SDCH in Exit 7 is ignored if it is used with a printer that supports sending the default character with the LCPC IPDS command.