This is a purely informative tag, and tells users the size of the file in kB (Kilobytes). This data will change as content is added to each file, so it is useful to rewrite it from time to time.

<extent>≈680kB</extent>

Since size is always approximate, we use the Unicode character almost equal to, the double tilde that indicates approximation, to indicate this. On a Mac keyboard, insert it using alt+may+=. Its html entity is ≈.

The official abbreviation of kilobyte is kB. A kB contains 1024 bytes. The best way to know the ‘weight’ of our document is to consult the properties of the document in the file navigator.