Actually, Retired Helper ... there was quite a debate within UL as to whether to get the ISO certification. One of the arguments 'against' was that doing so would put them on the same plane as any other "ISO" testing lab .... meaning that there was an opening for competitors to spring up.

And, that is exactly what has happened. Today there are myriad places testing "to" various UL standards. Assuming the other place also has ISO certification, then the AHJ has no choice but to accept it.

I am aware that the basic language of the ISO rule is deceptively simple. Keep in mind that this whole ISO thing was kicked off by the desire of major manufacturers to "open up" their supply chain to new sources. The sundry ISO audits and documentation exist to reassure the final customer that all the requirements were met.