One for the "Pet Peeve" catagory

That's what I asked him. He would say it was undefined, then defined, then undefined, ect.

Apparently, they do come in various sizes. :)

As stated earlier: "THAT big (pointing)."

Where the thing is that is being pointed at depends on the locale.

In North America, the 'thing' is approximately .166044 inches in length.

In most of Continental Europe, the equivalent thing is about 6.5% bigger.

Liar.

Facts:

No uniform "theoretical" definition (in terms of a different unit of measure) exists.

No _single_ international standard exists.

"Trade associations", or similar, in various locales have agreed on a standard for _their_ locale. These 'agreements' are not necessarily consistent, nor do they necessarily even use the same methodology.

Many use a 'mark' as the official reference.

The low-end computerized typesetting trade uses a "derived" definition, wherein a pica is _exactly_ 1/6 of an inch. this is about 1/3 of 1% larger than the 'traditional' unit in North America.