From a 2 x 2. 
 Leaders Box Circulate twice and 1/4 In (Box Transfer) 
  as Trailers Box Circulate, 1/4 In, and Box Circulate. 
 Ends in a 2 x 2. 
| |   |  |   |  | before Single Checkmate
 |  | after 
 | 
 | |   |  |   |  | before Single Checkmate
 |  | after 
 | 
 | 
Notes:
- 
 Original Trailers can not Roll.  Single Checkmate is the Single version of 
    Checkmate The Column [A2].  
    Note that on Checkmate The Column, the Trailing two cannot Roll since their last
    part is to Step Ahead. 
- 
 Single Checkmate has historically been known as
    Split Checkmate when done on each side
    and Box Checkmate when done in the center
    or from a Box. 
 Cheat: Box Counter Rotate 1/4; Box Circulate.  This cheat
  emphasizes that only the original Leaders can Roll.  Some other
  glossaries list a similar cheat (Box Circulate; Box Counter
  Rotate 1/4) which makes it seem as if everyone can Roll. 
Checkmate The Column [A2] (H.P. Williams 1975):
 From Columns.  
  First Two Circulate 4 spots &
  1/4 In as Last Two Circulate twice, 1/4 In, & Circulate.
  Normal Columns end in Parallel Two-Faced Lines.
 See also Single CONCEPT [C3A,C3B,C4].