So I've got the document (160 USD for 40 pages!). Here is what it says in page iv:
The first edition cancels and replaces ISO 31-11:1992, which has been technically revised. The major technical changes from the previous standard are the following:
- Four clauses have been added, i.e. "Standard number sets and intervals", "Elementary geometry", "Combinatorics" and "Transforms".
Interestingly, it goes on saying that the standard's title "Quantities and units — Part 2: Mathematical signs and symbols to be used in the natural sciences and technology" should be renamed into "Quantities and units — Part 2: Mathematics".
Given the amount of copyright notices and other efforts to keep the standard from being diffused, I hope I don't get sued for quoting one sentence...