DEFINE Laengenmessung
  READ PNT 'Konturstart fuer Laengenmessung antippen ' Sp
  LET Laenge 0
  LET Zaehler 0
  LET Fp (Sp)
  LET Pp (Sp)
  LET Ap (Sp)
  LET Beginn (1)
  LOOP
    INQ_ELEM Pp
    IF (Beginn=0)
      UNDO
      IF (P1=P2)
        POINT P2)
      END_IF
    END_IF
  EXIT_IF ((Beginn=0) AND (Pp=Sp))
    LET Elementtyp (INQ 403)
  EXIT_IF (Elementtyp=
    END)
    IF (Elementtyp=
      LINE)
      LET P1 (INQ 101)
      LET P2 (INQ 102)
      LET Len_inc (SQRT (X_OF (P1 - P2)^2+Y_OF (P1 - P2)^2))
    ELSE_IF (Elementtyp=
      BSPLINE)
      LET P1 (INQ 101)
      LET P2 (INQ 102)
      LET Len_inc (READ_LTAB 'BSpline_basic_table' TITLE 2)
    ELSE
      IF ((Elementtyp=
        ARC) OR (Elementtyp=
        FILLET))
        LET P1 (INQ 102)
        LET P2 (INQ 103)
        LET Len_inc (ABS (INQ 4 - INQ 5)*6.28318530717959*INQ 3/360)
      ELSE
        IF (Elementtyp=
          POINT)
          LET P1 (Inq101)
          LET P2 (Inq101)
          LET Len_inc 0
          COLOR (INQ 201)
          LINETYPE (INQ 301)
        ELSE
          DISPLAY Elementtyp
          DISPLAY 'unzulaessiges element, ende konturverfolgung'
          EXIT
        END_IF
      END_IF
    END_IF
    IF (P1<>Fp)
      LET Hp (P1)
      LET P1 (P2)
      LET P2 (Hp)
      LET Dreh_sinn (1)
    ELSE
      LET Dreh_sinn (0)
    END_IF
    LET Fp (P2)
    IF (Elementtyp=
      POINT)
      DELETE Pp
      DELETE Ap
    ELSE
      DELETE Pp
    END_IF
    LET Ap (Pp)
    LET Pp (Fp)
    LET Beginn (0)
    LET Laenge (Laenge+Len_inc)
    LET Zaehler (Zaehler+1)
  END_LOOP
  END
  DISPLAY ('Messung von '+STR Zaehler+' Elementen ergab eine Laenge von ==>'
  +STR Laenge)
END_DEFINE