Any finite sequence of primitive symbols is not always well-formed in the usual formalisms. But in a certain formal system, we can normalize any sequence of symbols uniquely so that it becomes well-formed. An example of this kind has been introduced by Ono [2]. While we were drawing up a practical programming along Ono’s line, we attained another system, a modification of his system. The purpose of the present paper is to introduce this modified system and its application. In 1, we will describe a method of normalizing sentences in LO having only two logical constants, implication and universal quantifier, so that any finite sequence of symbols becomes well-formed. In 2, we will show an application of 1 to proof. I wish to express my appreciation to Prof. K. Ono for his significant suggestions and advices.