The media map must be updated anytime a file is created, recreated, renamed, deleted, or moved. In addition, a media map may need to be updated for such functions as MFS installation.
In order to access the media map, OpenInsight generates special media access calls. There are calls to initialize, open, read, and write to the media map.
Because the media map is much like a file, access to the media map is much like file access. As with file access, much activity in the media map requires an internal media handle.
The media handle is created by the OPEN.MEDIA call. If successful, this call returns a handle that is used in subsequent media access calls such as READ.MEDIA and WRITE.MEDIA. As with the file handle created by OPEN.FILE, the media handle is stored by the system. The handle returned by OPEN.MEDIA is kept in the SYSVOLUMES file as field five.
