DDSXTY13 — Organization of section 7.2.2.4.4 is confusing

Section 7.2.2.4.4 'Aggregated Types' has a confusing organization of its sub-sections. It mixes at the same level description of common aspects of Aggregated types (e.g. members names, types, properties like being optional etc). With the classification of 'Aggregated Types' into "Structures' and 'Unions'.

Moreover the concept of "member index" is not explicitly defied even if it appears in the figures and UML model. The text does talk about a "declaration order" for members but does not tie it to the "member_index" concept.

It would be better if the subsections were reorganized. Rather than:

7.2.2.4.4.2 Structure Types
7.2.2.4.4.3 Union Types
7.2.2.4.4.4 Member IDs
7.2.2.4.4.5 Members That Must Be Understood by Consumers
7.2.2.4.4.6 Optional Members
7.2.2.4.4.7 Key Members

It would be better if it was:
7.2.2.4.4.1 General
7.2.2.4.4.2 Structure Types
7.2.2.4.4.3 Union Types
7.2.2.4.4.4 Members of an Aggregated Type
7.2.2.4.4.4.1 Member Name
7.2.2.4.4.4.2 Member Type
7.2.2.4.4.4.3 Member Index
7.2.2.4.4.4.4 Member ID
7.2.2.4.4.4.5 Must Understand Members
7.2.2.4.4.4.6 Optional Members
7.2.2.4.4.4.7 Key Members

This reorganization should be applied before other issue resolutions that affect the section as they would benefit from the more logical section numbering.

Reorganize section 7.2.2.4.4 as suggested in the issue description

Apply the suggested reorganization