       scanmatch ?-nocase? contexthandle ?regexp? commands
              Specify  Tcl  commands, to be evaluated when regexp
              is matched by a scanfile  command.   The  match  is
              added  to  the  scan  context  specified by contex-
              thandle.  Any number of  match  statements  may  be
              specified  for a give context.  Regexp is a regular
              expression (see the regexp command).  If -nocase is
              specified  as  the  first  argument, the pattern is
              matched regardless of alphabetic case.

              If regexp is not specified, then a default match is
              specified  for the scan context.  The default match
              will be executed when a line of the file  does  not
              match any of the regular expressions in the current
              scancontext.

              The array matchInfo is available to  the  Tcl  code
              that  is  executed  when  an expression matches (or
              defaults).  It contains information about the  file
              being  scanned  and  where within it the expression
              was matched.

              matchInfo is local to the top level  of  the  match
              command unless declared global at that level by the
              Tcl global command.  If it  is  to  be  used  as  a
              global,  it must be declared global before scanfile
              is called (since scanfile sets the matchInfo before
              the  match  code  is  executed, a subsequent global
              will override the local variable).   The  following
              array entries are available:

            matchInfo(line)
                   Contains the text of the line of the file that
                   was matched.

            matchInfo(offset)
                   The byte offset into the  file  of  the  first
                   character of the line that was matched.

            matchInfo(linenum)
                   The  line number of the line that was matched.
                   This is relative to the  first  line  scanned,
                   which  is  usually,  but  not necessarily, the
                   first line of the file.   The  first  line  is
                   line number one.

            matchInfo(context)
                   The  context  handle  of the context that this
                   scan is associated with.

            matchInfo(handle)
                   The file id (handle)  of  the  file  currently
                   being scanned.
            matchInfo(copyHandle)
                   The  file id (handle) of the file specified by
                   the -copyfile option.  The  element  does  not
                   exist if -copyfile was not specified.

            matchInfo(submatch0)
                   Will contain the characters matching the first
                   parenthesized subexpression.  The second  will
                   be contained in submatch1, etc.

            matchInfo(subindex0)
                   Will  contain  the  a list of the starting and
                   ending indices  of  the  string  matching  the
                   first parenthesized subexpression.  The second
                   will be contained in subindex1, etc.

       All scanmatch patterns that match a line will be processed
       in  the  order in which their specifications were added to
       the scan context.  The remainder of the scanmatch pattern-
       command pairs may be skipped for a file line if a continue
       is executed by the Tcl code of a preceding,  matched  pat-
       tern.

       If  a return is executed in the body of the match command,
       the scanfile command currently in progress  returns,  with
       the value passed to return as its return value.

       This command is provided by Extended Tcl.
