General Order 64-A
Section II
Definitions Of Terms Used In This Order
22.6 Sag includes either Normal or Apparent, as defined in the following definitions:
A. Normal Sag means the difference in elevation between the highest point of support of a span and the lowest point of the conductor in the span at 60°F and no wind loading (see App. G, Fig. 4).
B. Apparent Sag means the maximum departure, measured vertically, of a wire in a given span from a straight line between the two points of support of the span at 60°F. and no wind loading. Where the two supports are at same level, this will be the normal sag. (see App. G, Fig 5.)