(Also see "Roof Drainage")
1. General: An excellent general piece on scuppers is available here at the website of the Copper Development Association. They talk about scuppers being made out of copper in that article, but that doesn't mean that scuppers are necessarily made out of copper.
2. Codes: "(P) 1503.4.1 Secondary (emergency overflow) drains or scuppers" in the 2015 International Building Code.