1) Concerning altitude flight level, the term means to remain at the altitude flight level specified. The phrase "climb and" or "descend and" normally precedes "maintain" and the altitude assignment; e.g., "descend and maintain 5,000". 2) Concerning other Air Traffic Control (ATC) instructions, the term is used in its literal sense; (e.g., maintain Visual Flight Rule (VFR)).
(FAA4)