From any Line of 4.
Centers Run as Ends Cross Run.
Ends in a Line.
| |   |  |   |  | before Switch The Line
 |  | after 
 | 
 | |   |  |   |  | before Switch The Line
 |  | after 
 | 
 | 
Notes:
- 
You may wish to think of Switch The Line as (do your part) Swing-Slither.
- 
At A2, Switch is restricted to starting only from a Wave.
- 
According to the CALLERLAB definitions, in cases where dancers would
    collide, those doing the Cross Run move outside of those doing the Run;
    otherwise, all the usual shoulder-passing rules apply.
Grand Switch (The Line | Wave) [C4] (Lee Kopman):
 From a general 1 x {n} Line. 
  The #2 dancers (those adjacent to the Very Ends) Run as the others 
  Grand Working As Ends 
  Cross Run.
  Ends in a 1 x {n} Line.  
  Cheat: As one movement, Swing-Grand Slither.
 See also Cross Roll To A Line | Wave [C1].