/*
 * TYPEDEF: SE_Transmittal
 *
 *   Handle to a transmittal. The definition of a transmittal
 *   is hidden by the implementation of this API. The user of this API simply
 *   passes in and receives back an SE_Transmittal for functions that deal
 *   with a transmittal.
 *
 *   A transmittal is a collection of DRM objects stored in a
 *   particular format (or set of formats) that can be accessed via a
 *   single implementation of the SEDRIS API. Typically, this implies
 *   some set of media-based "files" or other units of allocation.
 *   A key attribute of a transmittal is that when
 *   conveyed from one location, system, or human organization, to another,
 *   all the parts (files, etc.) must be conveyed together in order for the
 *   data to be fully accessible by the software applications that invoke the
 *   read (or write) API implementation. It is as if all the parts must be
 *   considered as one physical entity. A transmittal may refer to
 *   other transmittals for describing the portions of its
 *   environmental data that are intentionally included in other
 *   transmittals.
 *
 *   Note that a transmittal is distinct from a "Unified Environment".
 *
 *   A unified environment is a logical collection of data describing a
 *   representation of some aspect of an environment (natural, man-made, or
 *   fictitious) used in a computer based application or other automated
 *   systems. In SEDRIS, a Unified Environment is formed from DRM objects
 *   and the relationships between these objects. A complete unified
 *   environment may span multiple transmittals, via relationships
 *   formed using Inter-Transmittal References (ITR).
 */