Not being a Crystal person I would hope the customize menu has a separator value of some type but based on the link below, I don't see one.
http://www.c-sharpcorner.com/UploadFile/mahesh/DateFormatInCR06132007092248AM/DateFormatInCR.aspxYou might need to go with the custom method:
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In that case, you do not see the Date and Time tab on the Format Editor.
In this situation, you rely on your own code.
ToText function comes handy to do all formatting. For example, I need a date formatting as following: 23-Mar-2007
The following formula will do the trick:
ToText({MYFIELDNAME }, "dd-MMM-yyyy")