This example takes a date and determines if it is a week day or a weekend. The basic approach for this relies on the simple fact that the only days (in English) that begin with the letter "S" are the days of the weekend.
The workflow begins by capturing a date. This is then formatted using the "EEEEE" format string to return the first letter of the day of the week for that date. If this is "S" then an alert is shown identifying the date as a weekend day. If this is not an "S" then an alert if shown identifying the date as a weekday day.