What should be used to control the movement of a swing-away lattice extension when erecting or stowing it?

Using a tag line is the appropriate method for controlling the movement of a swing-away lattice extension when erecting or stowing it. A tag line is a secondary line used to guide and control the load during lifting operations, providing operators with better control over the load's swing and allowing for precise positioning. This is particularly important in situations where the load may be difficult to manage, as it helps to prevent uncontrolled movement which could lead to accidents or damage. The use of a tag line ensures safety and enhances the efficiency of the rigging process, especially in tight or challenging environments.

Other methods, while useful in different contexts, may not provide the same level of control. For example, an auxiliary crane is used for lifting additional loads but isn't necessary or practical for managing a single lattice extension. A come-along is a tool for pulling or tensioning but does not provide the necessary control during the actual movement of the lattice extension. Similarly, a nylon round sling is designed for lifting and securing loads but does not serve the purpose of controlling lateral movements. Therefore, the tag line is essential for managing the dynamic aspects of erecting or stowing a swing-away lattice extension safely.