Parameters

 

n

   The number that the next .CHAPTER will have. Entering the .NUMBER
   CHAPTER command without an argument gives Chapter 1.
 

+n

   Adds n to the number of the most recently issued .CHAPTER. The
   result is the number that the next .CHAPTER will have.
 

-n

   Subtracts n from the number of the most recently entered
   .CHAPTER. The result is the number that the next .CHAPTER will
   have.