Contents of this chapter:
15.1. NET-SIGNAL-GROUP
15.2. NET-SIGNAL-GROUPS
15.3. NET-SIGNAL-REF
15.4. NET-SIGNAL-SPEC
15.5. NET-SIGNAL-SPEC-VARIANT
15.6. NET-SIGNAL-SPEC-VARIANTS
15.7. NET-SIGNALS
15.8. NET-TOPOLOGY-SPEC
15.9. NMLIST
15.10. NODE-TYPE
15.11. NODE-VARIANT
15.12. NOTE
15.13. NUMBER