I've heard the term cords before. Cords are especially common in high-lead glass - or especially hard to avoid, anyway. I guess they call them cords because they can be long and thin, like a string. Interesting that they talk about it, and say perfection is rarely achieved - sounds like they have a problem with them. It doesn't seem to be much of an issue in ABP glass that I know of. I'll have to look into that.
I wonder how long they've been using acid polishing.
Nice little article! Thanks for posting it.