Gets the current clipboard contents in a specific format, returning null if the clipboard does not contain data in the requested format.
The format string is typically four capital letters. (On the Macinotsh, only four characters for format are ever used.) For example, "TEXT" is the name of the simple text format. New format names can be used to communicate application-specific kinds of data through the clipboard.
See Cut and Paste for a discussion of the time argument.