Wireshark · Wireshark-dev: Re: [Wireshark-dev] 12 byte number

[Guy Harris <guy@xxxxxxxxxxxx>]

On Aug 22, 2008, at 6:26 AM, Martin Corraine (mcorrain) wrote:

> The spec describes the value as a 96-bit identifier that can range  
> from
> 0 to 2^96 - 1. It serves as an id to track messages. So I think it's
> just a very large unsigned number. When you say opaque value, what do
> you mean by that?

I mean that it's not interpreted as anything other than a pile of bits  
- i.e., if it happens to have the value 17, that doesn't mean, for  
example, that anything referred to by the packet is 17th of a set of  
things (or 18th of a set of things), or that there are 17 things of  
some sort, or that something has type 17, or....

It sounds as if that's what the identifier is - just a pile of bits  
(assuming that message IDs aren't required to be sequential) - so  
FT_BYTES is the right data type.  If it were a value whose numeric  
value was significant in and of itself (rather than just as a message  
ID to be matched between, say, requests and replies), that might call  
for a data type to support larger numeric values.