I'm thinking somebody might find this useful.

My Ofmega quick release skewers have the lever held on with e-clips (external circlip ?).
Naturally when I bought the bike one of them was broken and replaced with some wire.
So I got some e-clips from Amazon and just about got a 4mm one to fit after quite a lot of thumb damage.

The correct size is 3/16" IMPERIAL, and will go on in 5 seconds using some pliers.

I am guessing that these are called "e-clips" because their three contact points make them resemble a (very stylized) capital letter "E".

Doh, you're probably right

Would e-clip skewer be interchangeable with the bolt Ofmega skewers. I need to change the shaft.

Should be, just measured mine at 4.9mm diameter shaft which is standard.
You need to check the length, but you can always cut a bit off the end if they are too long.

I read the question as replacing the complete skewer.