Representing a cumulative 'best practice' the Railways Clearing House (RCH) specifications were agreed with the major railway companies for service throughout Great Britain and defined a number of standard parts, fittings and requirements for design, strength and safety. Some individuality in detail design by the builders was allowed, but the standardised of parts, particularly those parts which might need repair or replacement in service, ensured that a RCH standard wagon could be repaired more quickly.
Wagon owners no doubt welcomed this, as their railway wagons represented a major capital investment and if it wasn't moving it couldn't earn them money!