2015 ORS § 161.555¹
Classification of misdemeanors

(1) Misdemeanors are classified for the purpose of sentence into the following categories:

(a) Class A misdemeanors;

(b) Class B misdemeanors;

(c) Class C misdemeanors; and

(d) Unclassified misdemeanors.

(2) The particular classification of each misdemeanor defined in the Oregon Criminal Code is expressly designated in the section defining the crime. An offense defined outside this code which, because of the express sentence provided is within the definition of ORS 161.545 (Misdemeanor described), shall be considered an unclassified misdemeanor.

(3) An offense defined by a statute of this state, but without specification as to its classification or as to the penalty authorized upon conviction, shall be considered a Class A misdemeanor. [1971 c.743 §70]