- SPF(Line-Numbered 80byte fixed length) file.
     .Special case of margin specified file.
      This type file has line number field on the line end and
      all line has same length.
      Specify option=(N) on CID header line.
      It is easy, on PC, to maintenance main frame punched card file
      (80 byte fixed record length text file).
      Line number field(on Right margin) is input protected and
      page shift scroll width is limited up to the line end.
      EB/BB/SB cmd(alias of Edit/Browse/Select cmd with /Mn option)
      treat file without CID header as Line-Numbered-File
     .Line number field format is nnnnssuu.
      nnnn:line number  ss:suffix  uu:update level
      Maximum update level number among all lines is assigned to the
      file, and File update level number +1 is set to all updated line
      when save.
      Size of line number display column on the left of screen is
      set to 7 at file open and of nnnnsss format.
     .If invalid line(wrong length, not numeric line number field,line
      number sequence err) exist at open, use RENum cmd to correct it
      (cutting or space padding to the fixed length then renumber).
     .Line number field protection is reset when wrong line detected
      at copy operation by Copy cmd/Copy line cmd.
     .Update level number is displayed or changed by VER cmd.
      If file update level is changed downward, each line update level
      is changed downward relative to the level of command operand
      at save file(max is the level, min is 1).If it is changed to
      upward, only updated line is set to the new level.
      This operation is undo-able.
     .All Tab is replaced by space at save.
     .Also CID can be set to Line-Numbered-File.
     .COBOL is one of Line-Numbered-File.
      COBOL lineno is on col1-6.Col 73-80 is optionally line number column.
      Without option=(n),CID may set on the 73-80 column.
      Col1-6 may be optionally all space.
      Renum,num clear,indentation and display start offset function
      consider COBOL file.