What are the secret options of the PDF convert tool from OS X? I recently discovered the /System/Library/Printers/Libraries/convert tool that is able to convert HTML, DOC, ... to PDF. 

It works great but it has some optional arguments that are not documented: -a 'name=value ...'. I am really interested about them because these are supposed to control more of the 'printing' process.

/System/Library/Printers/Libraries/convert
Usage: convert [ options ]

Options:

  -e                   Use every filter from the PPD file
  -f filename          Set file to be converted (otherwise stdin)
  -o filename          Set file to be generated (otherwise stdout)
  -i mime/type         Set input MIME type (otherwise auto-typed)
  -j mime/type         Set output MIME type (otherwise application/pdf)
  -P filename.ppd      Set PPD file
  -a 'name=value ...'  Set option(s)
  -U username          Set username for job
  -J title             Set title
  -c copies            Set number of copies
  -u                   Remove the PPD file when finished
  -D                   Remove the input file when finished
The options for the CUPS system are mainly for specifying borders, margins, how many pages per sheet, etc. They are documented on the CUPS website:

http://www.cups.org/documentation.php/options.html