From a Wave, Inverted Line or other applicable formations.
Centers Step Ahead (1/2 Press Ahead) as Ends Fold.
A Wave ends in a Mini-Wave Box, an Inverted Line ends in Tandem Couples.
Step & Fold is a very important call, since it is used in the
  definitions of many other calls.  Learn it well and be able to execute it
  precisely.
Step & Slide [A1] (Ed Fraidenburg 1967):
 From any Line of 4 or other applicable formations.  
  Centers Step Ahead as Ends Slide together.  
  A Line of 4 ends in a 2 x 2 or a "Z".
Grand Step & Fold [C1V]:
 From an applicable Line of 6 or 8 or other applicable formations.  
  Very Ends Fold as the others Step Ahead.  
  A Tidal Wave ends in Parallel 3 & 1 Lines.
| |   |  |   |  | before Grand Step & Fold
 |  | after 
 | 
 | 
Step & Cross Fold [C4]:
 From a Two-Faced Line or other applicable formations.  
  Centers Step Ahead (Press Ahead) as Ends Cross Fold.  
  A Two-Faced Line ends in a Mini-Wave Box.
| |   |  |   |  | before Step & Cross Fold
 |  | after 
 | 
 | |   |  |   |  | before Step & Cross Fold
 |  | after 
 | 
 | 
 See also  
Step & Flip [C1]
 and Step And anything [C2].