How does the clipboard work in Windows?
It is a system wide bit bucket, which means it just holds a sequence of bytes and an integer value (a windows atom) which describes it's format - but does not ensure that the byte sequence is really this format.
The only feature other then this is that an application can decide if it wants the system to store the byte sequence or if the application keeps the data itself and only provide it when someone is requesting it.
So as you see it is an API and not a data structure.
If you're using the Win32 API, here is the reference:http://msdn.microsoft.com/en-us/library/ms649014(VS.85).aspx
Quick, lazy Google search got this; hope it helps a bit:
http://msdn.microsoft.com/en-us/library/system.windows.clipboard.aspx