Editing Old Japanese (section)

===Phonotactics===
Old Japanese words consisted of one or more [[open syllable]]s of the form (C)V, subject to additional restrictions:
* Words did not begin with ''r'' or the voiced obstruents ''b'', ''d'', ''z'', and ''g'', with the exception of a few loanwords.{{sfn|Frellesvig|2010|p=43}}
* A bare vowel did not occur except for word-initially: vowel sequences were not permitted.{{sfn|Frellesvig|2010|p=39}}

In 1934, [[Arisaka Hideyo]] proposed a set of phonological restrictions permitted in a single morpheme. Arisaka's Law states that ''-o<sub>2</sub>'' was generally not found in the same morpheme as ''-a'', ''-o<sub>1</sub>'' or ''-u''.
Some scholars have interpreted that as a vestige of earlier [[vowel harmony]], but it is very different from patterns that are observed in, for example, the [[Turkic languages]].{{sfn|Frellesvig|2010|p=44}}