Since 'A new era name should be established,' it seemed that the characters were changed and the pronunciation was changed to "yamaki," but in fact, only the characters were changed to "山城" and "yamashiro," "城" was pronounced "shiro" only for the word "山城."
「新号を制すべし」とあるから、改字にとどまらず、称号も“やまき”としたのかもしれないが、実際は字だけを「山城」と改めて、なお“やましろ”と訓じたので、「山城」という文字列についてだけ、“城”に“しろ”の訓が生じた。