TYPERULES(5F)															     TYPERULES(5F)

NAME

       typerules - HylaFAX file type identification and conversion rules

DESCRIPTION

       Only  three types of files are accepted by the HylaFAX server for transmission as facsimile: POSTSCRIPT(R) files, PDF files, and TIFF Class
       F (bilevel Group 3-encoded) files.  All other types of files must be converted to one of these three  formats.	The  facsimile	submission
       program	applies  a  set  of rules against the contents of each input file to identify the file's type and to figure out how to convert the
       file to a format that is suitable for transmission.  These rules are stored in the file /usr/lib/fax/typerules, an ASCII file that is  pat-
       terned after the /etc/magic file used by the System V file(1) program.  However, there are significant differences, noted below.

       Type  rules  work  by matching data patterns in a file; typically patterns that appear in the first few bytes of the file (i.e.	magic num-
       bers).  There are two types of rules, primary rules and secondary rules.  Secondary rules specify additional rules to apply after a primary
       rule has been matched.  When secondary rules are used, rule scanning continues up to the next primary type rule in the file.

       Each rule consists of a set of whitespace-separated fields:
	    offset    datatype	  match    result   command
       If  an  line  is  terminated wth a backslash character, the entry is continued on the next line with any leading whitespace characters com-
       pressed to a single space.  Comments are marked with the ``#'' character; everything from to the end of the line is  discarded.	 Secondary
       rules have a ``>'' character in the first column of the line; primary rules do not.

       The fields in each rule entry are:

       offset	 The byte offset in the file at which data should be extracted and compared to a matching string or value.

       datatype  The  type  of	data  value  to extract at the specified offset for comparison purposes; one of: ``byte'' (8 bit unsigned number),
		 ``short'' (16 bit unsigned number), ``long'' (32 bit unsigned number), ``string'' (an array of bytes), ``istring'' (a case-insen-
		 sitive array of bytes), or ``ascii'' (an array of ASCII-only bytes).

       match	 The  value and operation to use in matching; the value used is based on the datatype field.  If value is ``x'', then it is inter-
		 preted to mean match anything; otherwise the following operators are supported (where data is the value extracted from  the  file
		 and value is specified in the match field) except for types ``string'', ``istring'', and ``ascii'':
		 =     data == value		  !=	data != value
		 >     data > value		  <	data < value
		 <=    data <= value		  >=	data >= value
		 &     (data & value) == value	  !	(data & value) != value
		 ^     (data ^ value) != 0

       If no operation is specified then ``='' is used.

       For ``string'', ``istring'', and ``ascii'' no operator is allowed; the implicit
       operation is always ``=''.  In these cases, the field is terminated by
       a tab or end of line, not by ``#''.  Characters in the field have
       their literal value; there are no C-style character escapes.

       result	 One  of ``ps'', ``tiff'', or ``error'' (case insensitive).  The first two results specify whether the rule generates a POSTSCRIPT
		 file or a TIFF/F file (Group 3-encoded bilevel data), respectively.  The ``error'' result indicates that a file is unsuitable for
		 transmission  and,  if supplied for transmission, should cause the job to be aborted with the command field used in an error mes-
		 sage.

       command	 A command description that is expanded and passed to the shell to convert the input file to the result format (suitable for send-
		 ing  as facsimile).  Before the string is passed to the shell, it is scanned and the following ``%'' escape codes are substituted
		 for:
		 %i	 input file name
		 %o	 output file name
		 %r	 output horizontal resolution in pixels/mm
		 %R	 output horizontal resolution in pixels/inch
		 %v	 output vertical resolution in lines/mm
		 %V	 output vertical resolution in lines/inch
		 %f	 data format, ``1'' for 1-d encoding or ``2'' for 2-d encoding
		 %w	 page width in pixels
		 %W	 page width in mm
		 %l	 page length in pixels
		 %L	 page length in mm
		 %s	 page size by name
		 %F	 the directory where HylaFAX filter programs reside
		 %<x>	 the <x> character (e.g. ``%%'' results in ``%''
       See below for example uses of these codes.

EXAMPLES

       The following rules are used to match the formats that are handled directly by the server:
       #offset	 datatype    match	    result    command
       0	 string      %! 	    ps			     # POSTSCRIPT
       0	 string      %PDF	    ps			     # POSTSCRIPT by Ghostscript
       0	 short	     0x4d4d	    tiff		     # big-endian TIFF
       0	 short	     0x4949	    tiff		     # little-endian TIFF

       These rules are used to process the ASCII version of IRIS Inventor database files while blocking the  transmission  of  the  binary  format
       variant:
       #offset	 datatype    match	    result    command
       0	 string      #Inventor V    error     IRIS Inventor file
       >15	 string      binary	    error     binary IRIS Inventor file
       >15	 string      ascii	    ps	      %F/textfmt -fCourier-Bold -p11bp
							  -U -q >%o <%i

       This rule is typically the last entry in the file and is used to convert all unmatched ASCII data files to POSTSCRIPT:
       #offset	 datatype    match	    result    command
       0	 ascii	     x		    ps	      %F/textfmt -fCourier-Bold -p11bp -U -q >%o <%i

NOTES

       It  is  much better to convert data that is to be transmitted to POSTSCRIPT because this data format permits the facsimile server to do the
       final imaging according to the optimal transfer parameters (resolution, binary encoding, etc.).

       It might be better to allow secondary rules to augment a primary rule rather than just replace them.  This would allow, for  example,  com-
       mand line options to be selected based on file type.

SEE ALSO

       sendfax(1), hylafax-client(1)

								   May 12, 1993 						     TYPERULES(5F)