What publication is published periodically and contains instruction that does not affect train movement?

The correct answer is Division Notice (DN) because this publication is specifically designed to provide employees with important information that may pertain to operations, safety, and administrative procedures without impacting the immediate movement of trains. It serves as a channel for communicating updates, clarifications, and instructions that are relevant to the ongoing operations of the railroad but do not dictate the direct control of train movement.

The other options, while also important publications, either impact train operations directly or do not fit the definition as closely. For instance, Operational Bulletins typically address specific operational procedures or changes that may influence train movement and operational compliance. Similarly, the Work Instruction Manual is focused on specific tasks or operational guidelines that manage or influence employee duties, which can include activities related to train movement. Employee Updates may also include critical operational information that impacts procedures but are broader in scope compared to the focused purpose of Division Notices. Thus, the Division Notice stands out as the publication that centers on information that does not alter train movements.