Md. Code Regs. 11.22.03.01
The standards, requirements, and procedures set forth in this chapter are applicable to equipment originally installed by the manufacturer or required by federal or State law or regulation on any vehicle registered as a Class M (multipurpose) passenger vehicle which has a seating capacity for 16 or more passengers including the driver or was previously registered as a Class H (school) vehicle or a Class P (passenger bus) vehicle, and which is used primarily to transport passengers, under the provisions of Transportation Article, Title 13, Annotated Code of Maryland, or any bus designed and used to carry more than 10 people owned by this State or any political subdivision of this State. Compliance with these minimum requirements may not be sufficient for the equipment to remain in compliance for 12 months or 25,000 miles, whichever occurs first. Therefore, more frequent maintenance, service, and repair as deemed necessary by the owner is permitted and recommended.
Md. Code Regs. 11.22.03.01