SetFAttr procedure

  DECLARATION:  SetFAttr(var F; Attr : Word);

      PURPOSE:  Sets the attributes of a file

         UNIT:  DOS

      REMARKS:  F must be a file variable (typed, untyped, or text) that
                has been assigned but has not been opened.  The attribute
                value is produced by adding the appropriate attribute masks
                as defined in the DOS unit as follows:

                         Const
                              ReadOnly    = $01;
                              Hidden      = $02;
                              SysFile     = $04;
                              VolumeID    = $08;
                              Directory   = $10;
                              Archive     = $20;
                              AnyFile     = $3F;

                NOTE: Errors are reported through DosError

 RESTRICTIONS:  File cannot be open