Why is the circumstantial appendix placed after faṣl and waṣl?

Appendix to Faṣl and Waṣl: Circumstantial Clauses, Wāw and Pronominal Linkage

• Every ḥāl necessarily has wāw
• Circumstantial clauses may be linked with or without wāw
• A ḥāl is always syntactically a naʿt
• Both topics concern rhyme only