[Jeff Morriss <morriss@xxxxxxxxx>]

Michael Lum wrote:

> I wanted to make the following changes to the MTP3 dissector:
>
> 1.  Add two hidden uint32 fields for 24bit OPC/DPC
> 	This allows display filtering using the complete 24 bit integer value
> 	as an alternative to something like "mtp3.ansi_opc == 214-170-26".
>
> 	i.e.  "mtp3.24bit_opc == 0x66aad6" or "mtp3.24bit_opc == 6728406"

Why not re-use "mtp3.opc" (normally used for ITU) in ANSI--but hidden?

An alternative to that (that I never had a chance to finish thinking 
about) is to make "mtp3.opc" a string (instead of an integer) and then 
add any values we want:
	- decimal
	- hex
	- 3-8-3 (ITU)
	- 8-8-8 (ANSI/China)

The disadvantages (that I have thought of) to doing that (and why I 
added "ansi_opc" instead of doing that at the time) are:
	- we'd have to sprintf() any values we want
	- it's possible filter expressions that rely on it being a number will 
break--but I don't know if anybody ever does "mtp3.opc > 1000" or if 
that's even allowed
	- not being an integer means we'd have to actually add decimal *and* 
hex (in case some people filter on decimal while others use hex)

The advantages are:
	- we could have a pref that chooses which of the formats are visible 
(the rest would remain hidden).  Or more than one could be displayed?
	- there'd only be one "mtp3.opc" instead of 2 or 3 or...