No - it's the hatch into the loft! I haven't yet worked out how the baseboards will go but it is intended to be walkaround, and will probably use DCC. Or radio control, but a bit tricky to fit into O2s especially those which already have boilers stuffed with lead and araldite! The only tricky bit to reach will be the return loop which will be a ceawl under. Athough everything will be demountable, in preparation for the inevitability of one day not being able to get up to the loft. By then hopefully some children will have left home and there will be spare bedrooms!