       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.  Multiple scan contexts may be defined
              and they may be reused on multiple 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  context,  {}  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.
