However, as opposed to Heptanesian, IC5 is also missing from loans due to a historical evolution, according to which many ancient nouns in -on (today's nouns of IC5) got restructured into nouns in -ion in early medieval period (Browning 1969), and with the ultimate loss of /o/, they emerged as IC6 nouns in -in.
With respect to Heptanesian, Romance -human loans, which fall into the neuter category, are distributed into two inflection classes, IC5 (nouns ending in -o in the citation form, as in 14) and IC6 (those ending in -i, as in 15).
Nevertheless, the choice of the particular type of inflection class, that is whether it would be IC5 or IC6, is rather ad hoc, since both inflection classes seem to be of almost equal productivity, at least in Heptanesian.
Neuter gender is also very frequent in Pontic loans, where most Turkish -human nouns ending in a consonant (21a), or in -i [i], -i [m],-u [y] (20b-e) are integrated as IC6 neuter nouns in -in:
2+] Latitud ([micron] ([micron] ([micron] ([micron] mg/L) mg/L) mg/L) mg/L) IC6
81[grados] 62,1 3,83 9,87 16,93 IC5 82[grados] 65,11 4,05 8,36 20,05 Local [CH.
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