From four people in line regardless of who faces out and who faces in: All "Face down the Line" (face the center of the line or wave) and pass by two dancers passing right shoulders (double pass thru). Finishes with two files of two back to back (completed double pass thru formation). NOTE: Tag the Line is not a double pass thru--it always required that dancers first change their facing direction by a quarter and then do a double pass thru. When Tag the Line is followed by the terms Right, Left, In, Out or Zig Zag, dancers who have finished the Tag movement individually make quarter turns as the call indicates. Right means all turn 1/4 right; Left means all turn 1/4 left; In means all turn 1/4 to face the center of the set; Out means all turn 1/4 to put their backs to the center of the set; Zig Zag means the lead dancer turns right and the trailing dancer turns left.
Willard Orlich 1969
This definition is from The Handbook of Modern Square Dancing by Jay King.
It is provided here for informational and educational purposes only.