This field specifies the media of distribution as electronic, copies, original etc.
The media for the 1st document is the list of selected documents will be suggested as default but this can be changed to another media.
(I.e. where a document is normally distributed via electronic media, you can change it for a specific event to, for example "copies" as may be the case when a physical update/redline activity is required).
When selecting a variety of document numbers the distribution media for all will be the same for a single distribution event.