elisp: Motion by Indent

 
 31.17.6 Indentation-Based Motion Commands
 -----------------------------------------
 
 These commands, primarily for interactive use, act based on the
 indentation in the text.
 
  -- Command: back-to-indentation
      This command moves point to the first non-whitespace character in
      the current line (which is the line in which point is located).  It
      returns ‘nil’.
 
  -- Command: backward-to-indentation &optional arg
      This command moves point backward ARG lines and then to the first
      nonblank character on that line.  It returns ‘nil’.  If ARG is
      omitted or ‘nil’, it defaults to 1.
 
  -- Command: forward-to-indentation &optional arg
      This command moves point forward ARG lines and then to the first
      nonblank character on that line.  It returns ‘nil’.  If ARG is
      omitted or ‘nil’, it defaults to 1.