[GNC] Another sort field like 'Class' in Quicken?

[Paul Kinzelman]

Quicken normally specifies transactions into Categories for filtering
for reports and such.

But it also has a nice feature to allow a user to sort on a second field
called 'Class' which can be specified for each transaction.

Gnucash has what appears to be an unused field which could be
used for the same purpose. If you view "Double Line", there's a
space to the right of the "Notes" field which currently can't be
used.

Has anybody suggested or thought about using the unused field
for this extra filtering purpose?