The rendering mechanism represents the way in which you want to exchange the data, for example, dynamic data exchange (DDE). The rendering format identifies the actual type or true type of the data, for example, text. To exchange data, both the source and target must know how to communicate with each other through the rendering mechanism and understand the particular format of the data.
The native rendering mechanism and format of the object is the mechanism that most naturally conveys the data, either where it is now, or where it can be put most easily. The format conveys all information about the data. For example, a spreadsheet cell has a location in a row and column of a spreadsheet. Rendering the spreadsheet cell in a simple text format would cause this information to be lost, so a more appropriate format should be chosen for its native rendering format.
A source application may be able to exchange data with a target through several mechanisms, such as:
Additionally, the source application might be able to render the data in various formats, that is, into various types. For example, a spreadsheet application could render its contents in a spreadsheet format or into a simple text format. The ability of the source application to render the data in some format might, itself, depend on the exchange mechanism used. The rendering mechanisms and formats that a source application can support, for each object dropped, are provided to the target through the hstrRMF field in the DRAGITEM data structure.
The target application may also be able to exchange data with the source through several different combinations of mechanism and format. The target is responsible for obtaining the data from the source in the format that they both support and that provides the highest level of information about the data.
While making this determination, the target must consider the exchange capabilities offered by the mechanism. For example, an OS/2 File exchange mechanism can provide only a snapshot of the data at the time the direct manipulation operation occurred. An exchange using DDE, on the other hand, offers the target an opportunity to remain informed about changes to the data.