Use of Syntax Elements

Greetings colleagues

Does anyone have any good examples of the elements used to describe command
line syntax in action?

The Microsoft Manual of Style for Technical Publications (MSTP) suggests
command line syntax is made up of:
. name of the command (bold)
. a set of choices ({ })
. separator for mutually exclusive choices (|)
. arguments (italics)
. optional items ([ ])
. repeated items (...)

The DITA synph element can include the following elements:
. codeph
. delim
. kwd
. oper
. option
. parmname
. sep
. var

Some of these elements are from the programming domain, and others from the
software domain. 

When trying to map the MSTP to the DITA synph elements, it seems that there
is no semantic element to indicate a set of choices, and possibly the
separator for mutually exclusive choices and repeated items. (I say possibly
because the <sep> element looks good at first as the separator, but the spec
seems to suggest it is used for something else.) 

Also confusing is the var element, which the spec description says is only
used in syntaxdiagrams, but in fact may occur within synph. 

I've come up with a simple syntax example of:

<synph>
  <kwd>ant</kwd> 
  <option>-f</option> 
  <var>filename</var> 
  <option>-logfile</option> 
  <var>filename</var> 
  <option>-verbose</option>
</synph>

Is this right? Should <var> have been <parmname>?

And how would I mark-up a slight more complicated example (from MSTP) of:
{[form.] [control.]|Printer.}FontSize[=points%]

Am I right in thinking this might be an under-documented area of DITA?

Tony Self