Windows has had clipboard format negotiation since the beginning. When an application copies data into the clipboard, it can do so in multiple formats. Each format can be rendered either eagerly or lazily by the application putting data into the clipboard.

https://msdn.microsoft.com/en-us/library/windows/desktop/ms6...

Applications that wish to get data from the clipboard can then enumerate the available formats and select the format that matches what they can use.

https://msdn.microsoft.com/en-us/library/windows/desktop/ms6...

http://www.mschaef.com/blog/tech/excel/what_is_in_your_clipb...