This structure is passed with a DM_RENDER message, from the target to the source window, after a drop has occurred. It allows the target window to inform the source of several important things. For example, where the source supports several different rendering mechanisms and/or formats, the target can specify which of these it wishes to use. Similarly, if the source supports both copy and move operations, the target can specify which it will use by means of the usOperation field of this structure.
Another important field is hstrRenderToName. This tells the source window where to place the data, so that the target will know where to find it. The precise interpretation of this depends on the rendering mechanism; for example, in the case of the DRM_OS2FILE rendering mechanism, it contains the fully qualified name that the file is to be given at its destination. Where the transfer of information between source and target window is a simple memory transfer, this field may be used to contain the name of a named shared memory object into which the source is to place the data.