We're probably getting beyond Creator's capabilities but is it possible.
We have a field in a table which first off pulls the "locations_room_ref;" from Locations table and concatenates a "/".
if (input.devices_room != null)
{
roomid = Locations[ID = input.devices_room].locations_room_ref;
input.device_ash_code = roomid + "/";
}
We would LOVE to have the number sequentially increment after the "/"
BUT
the number to start from 01 for each locations_room_ref
AND
be unique - Note the same locations_room_ref can be used many times but is unique for "Site"