When to use Unicode Normalization Forms NFC and NFD?

Question

The Unicode Normalization FAQ includes the following paragraph:

Programs should always compare canonical-equivalent Unicode strings as equal ... The Unico

Answer 1

1. NFC is the general common sense form that you should use, ä is 1 code point there and that makes sense.

2. NFD is good for certain internal processing - if you want to make accent-insensitive searches or sorting, having your string in NFD makes it much easier and faster. Another usage is making more robust slug titles. These are just the most obvious ones, I am sure there are plenty of more uses.

3. If two strings x and y are canonical equivalents, then
   toNFC(x) = toNFC(y)
   toNFD(x) = toNFD(y)

   Is that what you meant?