       scancontext ?option?
              This  command  manages  file scan contexts.  A scan context is a
              collection of regular expressions and commands to  execute  when
              that  regular  expression matches a line of the file.  A context
              may also have a single default  match,  to  be  applied  against
              lines  that do not match any of the regular expressions.  Multi-
              ple scan contexts may be defined and they may be reused on  mul-
              tiple  files.  A scan context is identified by a context handle.
              The scancontext command takes the following forms:

       scancontext create
              Create a new scan context.  The scanmatch  command  is  used  to
              define  patterns  in  the context.  A contexthandle is returned,
              which the Tcl programmer uses to refer to the newly created scan
              context in calls to the Tcl file scanning commands.

       scancontext delete contexthandle
              Delete  the  scan  context identified by contexthandle, and free
              all of the match statements  and  compiled  regular  expressions
              associated with the specified context.

       scancontext copyfile contexthandle ?filehandle?
              Set  or  return  the file handle that unmatched lines are copied
              to.  (See scanfile).  If filehandle is omitted,  the  copy  file
              handle is returned.  If no copy file is associated with the con-
              text, {} is returned.  If a file handle is specified, it becomes
              the  copy  file  for this context.  If filehandle is {}, then it
              removes any copy file specification for the context.
