A new tension setting is available for any wire or messenger that you may be interested in. It is called "Horizontal Tension".
With this setting you are setting the actual tension value in the wire at the maximum sag point within the span. The value in having this as an option is related to how wires are strung in practice. Multiple spans are tensioned at the same time, with the wires allowed to move in their attachment hardware at each pole in the process, all while measuring the tension at one specific pole. Regardless of elevation changes causing different tension measurements at each pole, the horizontal tension at the maximum sag point is exactly the same in all spans at that time. After the line is strung, the wires are more firmly attached/clamped at each pole.
The ability to set this option and value is available in the Span Editor for individual spans, or via the Multi-Span Editor for several spans at once.
As a reminder, the Multi-Span Editor is available if you check-off the "enable span selections" checkbox at the top of the Plan View, then select multiple spans and right-click on one of them to bring up the menu. This feature works for power wires and communication messengers. For communication messengers, it is best that individual messengers have a "tag" value to help distinguish which one is which, but it is not mandatory.