GDB/MI async output token field

Hi,

I'm slowly working through the GDB/MI output command functionality.

On this page,
https://sourceware.org/gdb/onlinedocs/gdb/GDB_002fMI-Output-Syntax.html#GDB_002fMI-Output-Syntax

The documentation says,
 Note that for all async output, while the token is allowed by the
 grammar and may be output by future versions of gdb for select async
 output messages, it is generally omitted.

 Frontends should treat all async output as reporting general changes in
 the state of the target and there should be no need to associate async
 output to any prior command. 

I searched through the GDB source code and can't find a single place
where this occurs.

Does anyone know how to make a token appear in the async record?
Did older versions do it?

If GDB is not using this feature, I propose we remove this information
from the manual until we actually need the functionality.

Thanks,
Bob Rossi