A Second Sample Manpage

cal [-mjy] [month [year]]

Three separate options:
-m Display Monday as first day of week
-j Display Julian dates
-y Display a calendar for the current year
An optional month
Only if the month is given, an optional year.

Note that this page lumps all options together. This makes it more difficult to read, but it's done frequently with single-character (short) options. Furthermore, you may actually enter multiple short options without a separate hyphen for each one.