[Guy Harris <gharris@xxxxxxxxx>]

Ian Batterbee wrote:

> I don't quite understand what you're describing there.. could you 
> describe an how this would look/feel if implemented ?

In the Columns item in the Preferences dialog, "Format:" would have an 
option named something such as "Field", and might have, to the right of 
it, a text entry box.  If, and only if, "Field" was the format selected, 
the text entry box would be active; the user could specify the name of a 
field.

The column in question would, for a given packet, be blank if the packet 
contains no instance of the field with that name, and would show the 
value of one of the instances of the field in the packet (it should 
probably be the first or last instance) if there's one or more instance. 
 The value would be displayed the same way it'd be displayed in the 
protocol tree if a proto_tree_add_XXX_format routine *wasn't* being used 
(although, for "enumerated" values, if the value corresponds to one of 
the strings in the value_string table, it might just show the string, 
not the numerical value).

> At the moment, the column code already has to look at the protocol ID to 
> determine what (if any) layer 3 addresses the packet contains, so to 
> test for and display any present vlan ID would seem to be much the same 
> logic that is already there to test for layer 3 addresses.

The VLAN ID might be one of the "frequently-specified values" that would 
"probably be given their own column type", as per my previous mail.