Table 1.6 - The definition relate to implementation e.g. "need inheritance" or "not complete" rather than the information that is undefined in this state

Added the following paragrapgh before table 1-6

During the life-cycle of communications concerning Intervals, different information may be available or required. For service performance, Start Duration and the Attachment Payload must be complete. These may not be available or required during service advertisement or other pre-execution processes. Table 1 6 defines the language used to discuss how the information in an Interval is completed.