काशिका वृत्ति (आचार्य वामन एवं जयादित्य - अष्टाध्यायी सूत्र-वृत्ति सम्पूर्ण सान्वय सटीक)

सार्वधातुकयोर्दीर्घः" - it doesn't double there. Wait, let's look at "पित्र्यम्" vs "पित्रियम्" vs "पित्रीयम्": Wait, why does L24 say "पितुरागतं पित्र्यम्"? Wait! Let's search the grammar rule: Is there a vārtika or something? Wait! In Ashtadhyayi: "ऋत इद्धातोः" (7.1.100) "रीङ् ऋतः" (7.4.27) Wait! Under 7.4.27: Does Kashika say: "क्ङितीत्येतन्निवृत्तम्, तेनेहापि भवति — पितुरागतं पित्र्यम्"? Wait, why would "पितुरागतं पित्र्यम्" be an example of रीङ्? Wait, if it were an example of रीङ्, पितृ + यत् would become *पित्रीयम्! Wait, could it be: "तेनेह न भवति"? No, "तेनेहापि भवति"! Wait, DOES Kashika have this? Wait! What if it says "पित्र्यम्" in some editions? Wait, let's search Google mentally for: "क्ङितीत्येतन्निवृत्तं" "पितुरागतं" Wait! Could it be: "पितुर्यत्" (4.2.100) -> प