a.For use with natural gas;
b.For use with liquified petroleum (propane);
c.Direct vent appliances for manufactured home (USA only) or mobile home OEM installation convertible for use with natural gas and propane when provision is made for simple conversion from one gas to the other (see 1.2.4-a and -b);
d.Direct vent appliances for manufactured home (USA only) or mobile home aftermarket installation for use with natural gas only or liquified petroleum (propane) gases only (see 1.2.4-b.);
e.Direct vent appliances for recreational vehicle installation for use with liquified petroleum (propane) gases only (see 1.2.4-c);
f.Direct vent appliances for recreational vehicle installation only convertible for use with natural gas and liquified petroleum (propane) gases when provision is made for the simple conversion from one gas to the other (see 1.2.4-c); and
g.For direct vent appliances for manufactured home (USA only) or mobile home OEM installation for use with liquified petroleum (propane) gases only (see 1.2.4-a).