Please also look at Vb6:
Tattha katamaṁ nāmarūpapaccayā saḷāyatanaṁ? Cakkhāyatanaṁ, sotāyatanaṁ, ghānāyatanaṁ, jivhāyatanaṁ, kāyāyatanaṁ, manāyatanaṁ — idaṁ vuccati “nāmarūpapaccayā saḷāyatanaṁ”.
Tattha katamo saḷāyatanapaccayā phasso? Cakkhusamphasso sotasamphasso ghānasamphasso jivhāsamphasso kāyasamphasso manosamphasso—ayaṁ vuccati “saḷāyatanapaccayā phasso”.
Tattha katamā phassapaccayā vedanā? Cakkhusamphassajā vedanā, sotasamphassajā vedanā, ghānasamphassajā vedanā, jivhāsamphassajā vedanā, kāyasamphassajā vedanā, manosamphassajā vedanā—ayaṁ vuccati “phassapaccayā vedanā”.
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San gets incorporated with namarupa-ja-salayatana, salayatana-ja-phasso. “Tiṇṇaṃ saṅgati phasso” is samphassa.