The following additional definitions are for constituent parts of a
message whose implementation is being described within an IMPDEF
message:

Alias: this is used to describe a group of components collected
together and named for frequent or repetitive use.

Component: this is used in a generic sense to apply to any item which
may be a part of, or referenced by a part of a MIG. Thus it may refer
to a segment, a segment group, a simple or composite element, a code
list or individual code or non-coded value. It may also refer to
structures such as an alias or a constraint within a MIG.

Constraint: this is used to describe a group of components with either
an explicit or implicit constraint expression, which may be named for
error reporting and context determination.

Source Message: this is used to refer to the original message
specification as published in the relevant standard by the responsible
authority.

Target Message: this is used to refer to the resultant message
specification produced by applying the restrictions, clarifications
and constraints contained within the MIG to the Source Message.


Contents of IMPDEF