The output produced by one driver (such as PostScript) may not work on other printer brands without modification. For example, "TRAY = 1" on one printer may map to "TRAY = UPPER" on another. Transforms can be used to automatically make this adjustment to a print job. This is particularly important in a Find-Me printing environment where a job rendered by one driver may not print correctly on another printer type without modifying the print job.

Much is possible with the power of transforms. Maybe it’s always enabling the "eco print" mode when an email is printed, or automatically removing the "stapling" option if accidently selected on a printer the does not support stapling. Another use-case is "virtual stationery". Legacy reports could for example have a logo automatically added to each page.

A language used to describe the appearance of a printed page e.g. PostScript, Printer Control Language (PCL).

Attributes in a PJL header define print job characteristics such as duplex, color, paper sizes, or media trays. Many printers rely on a PJL header, though many attributes are printer/manufacturer specific.

A transform script defines a transform process to apply to a print job’s PDL. Transform scripts are written in a very simple scripting Domain Specific Language (DSL).

The transform process refers to source and target print queues. A desired transform is applied when a job is transferred from a specific source queue (a global queue) to a specific target queue.

The following steps select the transform script to run for a redirection from printer type source to printer type destination which both use printer language language.

var = expression

e.g. x = 1

Evaluate the expression and assign the variable var with the result. If the expression contains any $[N] and/or %variable% tokens, they are replaced with their current values. To prevent variable substitution, include __no_replace__ in the variable name e.g. __no_replace__template.

IF condition THEN statement

e.g.

    IF duplex THEN pjl_duplex = "ON"
                    

Evaluate the condition expression, and if true execute the statement.

FIND pattern [options]

where the pattern is a regular expression (regex) or string.

FIND /regex/ [REPLACE text] [options]

FIND "string" [REPLACE text] [options]

FIND searches for the pattern (a string or a regex) in the spool file and assigns $0, $1, ... from the resulting regular expression capture groups. If the pattern is a string, then only $0 is assigned.

e.g

    FIND /<<.*?\/ProcessColorModel\s*\/(DeviceCMYK|DeviceGray).*?>>\s*setpagedevice/
                   

could set $0 to "<< /ProcessColorModel /DeviceCMYK >> setpagedevice" and $1 to "DeviceCMYK" on a match.

FIND pattern REPLACE text [options]

where the pattern is a regular expression (regex) or string.

e.g

     FIND "Letter" REPLACE "A4"
     FIND /(\w+)\s=\sGrayscale/ REPLACE "$1 = BlackAndWhite"
     FIND /MODE = \w+/ REPLACE "MODE = %my_var%"
     FIND /MODE = \w+/ REPLACE "MODE = %my_var%" 2000
                    

The FIND works as described above. Then REPLACE substitutes all the $[N] and %variable% values in the text, before replacing the string matched in the spool file with the substituted text.

ADD_HEADER text

e.g.

    ADD_HEADER my_header
                    

Insert the string text as a header in the spool file.

STRIP_HEADER

Strip any PJL, XPIF, PostScript or other header (that our developers know about) from the spool file.

DELETE_UNTIL text

e.g

    DELETE_UNTIL "%!PS-Adobe-3.0"
                    

Delete from the start of the spool file up to but not including the first occurrence of text.

INSERT ofs len text

e.g

    INSERT regex_ofs regex_len my_replacement
                    

Insert the string text at the spool file offset ofs, after deleting len bytes.

DELETE ofs len

e.g

    DELETE regex_ofs regex_len
                    

Delete len bytes from the spool file, starting at offset ofs.

It is equivalent to:

INSERT ofs len ""