Document Methodology Used to Share "loop" specific segments.

[Dixon Whitmire]

The 270/271 transactions share the same general loop nesting structure. Within the loop structure some of the segments such as DTP are the same between subscriber and dependent use-cases. We need to standardize and document on these segments are "shared" between these use-cases, so that we aren't doing things such as creating a subclass that does nothing, or plugging in a segment for a dependent that has a subscriber naming scheme.