From Generalized Columns.
Ends slide apart (to allow for two dancer-sized positions of space between
them) as Centers do two Phantom Column Circulates; all adjust to end such that
the resulting Lines are close together.
Some callers say File To A Wave when the call ends in
Parallel Waves, and File To A Line otherwise. Other callers
always say File To A Line, no matter what the ending
formation will be.
Variation: From a Butterfly, the caller can say Centers (Start) File
To A Line in
which case the Centers do two Phantom Column Circulates and all
adjust to end in adjacent Lines.
Magic File To A Line [C2V]:
Ends Spread apart as Centers do two Phantom Column
Circulates; all adjust to end in adjacent Lines.
For those of you who are checker-pushers, File To A Line is
choreographically equivalent to Centers Box Circulate as Ends