[USE] Document customizations of USE categories

src/gen-use-table.py

@@ -247,6 +247,7 @@ def is_BASE_OTHER(U, UISC, UDI, UGC, AJT):
 	if UISC == Consonant_Placeholder: return True
 	return U in [0x2015, 0x2022, 0x25FB, 0x25FC, 0x25FD, 0x25FE]
 def is_CGJ(U, UISC, UDI, UGC, AJT):
+	# Also includes VARIATION_SELECTOR, WJ, and ZWJ
 	return U == 0x200D or UDI and UGC in [Mc, Me, Mn]
 def is_CONS_FINAL(U, UISC, UDI, UGC, AJT):
 	return ((UISC == Consonant_Final and UGC != Lo) or
@@ -269,6 +270,7 @@ def is_HALANT(U, UISC, UDI, UGC, AJT):
 		and not is_HALANT_OR_VOWEL_MODIFIER(U, UISC, UDI, UGC, AJT)
 		and not is_SAKOT(U, UISC, UDI, UGC, AJT))
 def is_HALANT_OR_VOWEL_MODIFIER(U, UISC, UDI, UGC, AJT):
+	# Split off of HALANT
 	# https://github.com/harfbuzz/harfbuzz/issues/1102
 	# https://github.com/harfbuzz/harfbuzz/issues/1379
 	return U in [0x11046, 0x1134D]
@@ -285,6 +287,7 @@ def is_HIEROGLYPH_SEGMENT_END(U, UISC, UDI, UGC, AJT):
 def is_ZWNJ(U, UISC, UDI, UGC, AJT):
 	return UISC == Non_Joiner
 def is_OTHER(U, UISC, UDI, UGC, AJT):
+	# Also includes BASE_IND, Rsv, and SYM
 	return ((UGC in [Cn, Po] or UISC in [Consonant_Dead, Joiner, Modifying_Letter, Other])
 		and not is_BASE(U, UISC, UDI, UGC, AJT)
 		and not is_BASE_OTHER(U, UISC, UDI, UGC, AJT)
@@ -294,6 +297,7 @@ def is_OTHER(U, UISC, UDI, UGC, AJT):
 def is_REPHA(U, UISC, UDI, UGC, AJT):
 	return UISC in [Consonant_Preceding_Repha, Consonant_Prefixed]
 def is_SAKOT(U, UISC, UDI, UGC, AJT):
+	# Split off of HALANT
 	return U == 0x1A60
 def is_SYM_MOD(U, UISC, UDI, UGC, AJT):
 	return U in [0x1B6B, 0x1B6C, 0x1B6D, 0x1B6E, 0x1B6F, 0x1B70, 0x1B71, 0x1B72, 0x1B73]