(under the class definition) Systems in which the physical possession by an officer of the train of a train staff, ticket, tablet, or other token is a prerequisite to entrance upon the section or block.
SEE OR SEARCH THIS CLASS, SUBCLASS:
77, through 80 and 247, for train-counting mechanism.
133, 134, 135, 141, 146, and 159, for details of electric locking and return-release indication.
