20amp IEC connector with a 15amp plug PC? ??

First I would bet the cord is not listed by UL or any other recognized testing agency.

Under UL guidelines a NEMA 5-15P plug, (15 amp), cannot be connected to a continuous load of more than 12 amps.
A NEMA 5-20P plug a continuous load of more than 16 amps.

NEC allows 2 or more NEMA 5-15R (15 amp) receptacles to be connected to a 20 amp branch circuit. (A duplex receptacle is two). But because of the requirements placed on the NEMA 5-15P the continuous load should never be more than 12 amps. NEC also says the receptacle shall not have a continuous load of more than 12 amps placed upon it.
Remember many 15 amp convenience outlets, receptacles, are connected to 15 amp branch circuits. That's why a 20 amp plug will not plug into a 15 amp receptacle.....

Now to your equipment with an 20 amp IEC connector. I doubt it would ever draw more than 12 amps continuous load. Continuous load? 3 or more hours..... Check the data plate on the back of the unit. Usually rated in watts or VA. Divide by 120V that will give you amps.

Rex, I concede to your challenge. Obviously I was wrong..... After doing some research I have found the IEC connectors are in a category all their own. The oddest thing I noticed the same connectors can be used for either 125Vac as well as 250Vac. To my knowledge I cannot think of any other plug and receptacle device that allows that here in the US.

The problem I have understanding the UL/CSA listing is where is the protection for the non savvy consumer that buys a piece of equipment that has a 20 amp IEC connector, that has a FLA rating of 16 amps, and did not come with the manufacturer supplied cord with a 20 amp plug. The guy that sold him the equipment lost the the factory cord and plug but threw in one that fit the IEC connector and had only a 15 amp plug.

The buyer knows beans about what we have been discussing here. He plugs the unit in, powers it up and everything seems to work fine. The branch he plugged into is only a 15 amp circuit and the wire is being overloaded. Hopefully the breaker will trip open. You would be surprised how many 15 amp breakers won't trip at 15 amps. Where is the protection.....
The cord and plug is not idiot proof, jmho.

Now here is an example that to me mirrors the same thing that is allowed with the IEC 20 / 5-15P power cord . As per NEC I cannot make a power cord with a NEMA 5-20R receptacle on one end and a NEMA 5-15P plug on the other end...... Can you see the difference?