Misdemeanors are classified for the purpose of sentence. When a statute does not specify the class, it is referred to as an unclassified misdemeanor. State laws vary on classification. In Oregon, according to ORS § 161.555 Misdemeanors are classified into
(a) Class A misdemeanors;
(b) Class B misdemeanors;
(c) Class C misdemeanors; and
(d) Unclassified misdemeanors.
It is further provided that
(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, 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.
ORS § 161.545 describes "Misdemeanor" as
A crime is a misdemeanor if it is so designated in any statute of this state or if a person convicted thereof may be sentenced to a maximum term of imprisonment of not more than one year.
Whereas in Wisconsin the classification is as follows:
Wis. Stat. § 939.51
(1) Misdemeanors in chs. 939 to 951 are classified as follows:
(a) Class A misdemeanor.
(b) Class B misdemeanor.
(c) Class C misdemeanor.
(2) A misdemeanor is a Class A, B or C misdemeanor when it is so specified in chs. 939 to 951
Unclassified misdemeanors or class u misdemeanors normally comes under moderate offenses . For Example driving with an expired license, with defective tail light, not paying parking tickets, driving while ability is impaired by alcohol and the like.
Example of some statutes in Arkansas on unclassified misdemeanors.
A.C.A. § 8-6-404 Penalties.
(a) (1) (A) (i) A person convicted of a violation of § 8-6-406 or § 8-6-407 for a first offense shall be guilty of an unclassified misdemeanor and shall be fined in an amount of not less than one hundred dollars ($100) and not more than one thousand dollars ($1,000).
§ 8-6-406 says about unlawful littering and § 8-6-407 says about Commercial refuse hauling by uncovered vehicles.
A.C.A. § 23-114-104 says about penalty under "Charitable Bingo and Raffles Enabling Act". It reads as follows:
(a) (1) A violation of this chapter by a licensed authorized organization is an unclassified misdemeanor and shall be punishable by a fine not to exceed five thousand dollars ($5,000).
(2) A second or subsequent offense is an unclassified misdemeanor and shall be punishable by a fine not to exceed ten thousand dollars ($10,000).
(b) A person who conducts a game of bingo or a raffle without a license under this chapter shall be subject to the same penalties as provided under § 5-66-118, concerning lotteries.