Understanding charms

Hope this is the correct spot for this topic.
Im curious about charms, after reading the Arreat Summit, I read that a SC can have “one or two” attributes. Does this mean it can have one Prefix or Suffix OR it can have one of each?
Can a sc have two suffix or two Prefix?

did you check one of these:

?

That did help, so it’s just 1 or the other OR 1 of each.
Meaning the most perfect SC (imo) would be a All res 5 / Life 20