I was under the impression that this is generally considered a bad idea because copyright law in some countries does not recognise the concept of a "public doma

I was under the impression that this is generally considered a bad idea because copyright law in some countries does not recognise the concept of a "public domain" (i.e. you can't disavow copyright even if you want to). I don't know if that's correct, but if so it would seem that something like the ISC (or modified BSD) license would be superior.