Synopsis Syntax (2)

Besides the optional brackets, there are two more common modifiers for options and arguments.

Ellipsis (three periods) signify multiple arguments of the same or similar form.
cat file [...] takes at least one file, but can take more.

The Pipe (vertical bar) signifies exclusive choices
rm [-f|-i] file [...] can take either -f or -i, but not both. (It also takes at least one file, but can take more.)