Code:
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(defun C:BLRED (/	   ALT-OS     ALT_BL	 BLCKLIST   BLLIST
		INDEX	   MADE_IT    NEU_BL	 OBJ_DAT    OBJ_KORD
		OBJ_LAY	   OBJ_NAME   OBJ_SC1	 OBJ_SC2    OBJ_SC3
		OBJ_WINK   SGET	      SGET_NAME	 SLENG
	       )
  (setvar "CMDECHO" 0)
  (setvar "FILEDIA" 0)
  (setq ALT-OS (getvar "osmode"))
  (setvar "OSMODE" 0)
  (command "_.ucs" "_w")
;;;  (setq BLLIST (list (cons "$TEMP$" "PFEIL")
;;;        ) ;_ end LIST
;;;  )
;;;  (setq BLLIST (list (cons "SS_HD" "G_SS")
;;;      (cons "SS_MD" "G_SS")
;;;      (cons "SS_ND" "G_SS")
;;;      (cons "S_HD" "G_S")
;;;      (cons "S_MD" "G_S")
;;;      (cons "S_ND" "G_S")
;;;      (cons "VS_HD" "G_VS")
;;;      (cons "VS_MD" "G_VS")
;;;      (cons "VS_ND" "G_VS")
;;;      (cons "AS_HD" "G_AS")
;;;      (cons "AS_MD" "G_AS")
;;;      (cons "AS_ND" "G_AS")
;;;      (cons "HAS_HD" "G_HAS")
;;;      (cons "HAS_MD" "G_HAS")
;;;      (cons "HAS_ND" "G_HAS")
;;;      (cons "WT_HD" "G_WT")
;;;      (cons "WT_MD" "G_WT")
;;;      (cons "WT_ND" "G_WT")
;;;      (cons "LS_HD" "G_LS")
;;;      (cons "LS_MD" "G_LS")
;;;      (cons "LS_ND" "G_LS")
;;;      (cons "VBS_HD" "G_VBS")
;;;      (cons "VBS_MD" "G_VBS")
;;;      (cons "VBS_ND" "G_VBS")
;;;      (cons "PFAHL_HD" "G_PFAHL")
;;;      (cons "PFAHL_MD" "G_PFAHL")
;;;      (cons "PFAHL_ND" "G_PFAHL")
;;;        ) ;_ end LIST
;;;  ) ;_ end setq
;;; Abwasserliste
  (setq	bllist
	 (list
	   (cons "W_BOHRUNG-SICHTBAR_11" "W_B-S_11")
	   (cons "W_BOHRUNG-SICHTBAR_11.1" "W_B-S_11.1")
	   (cons "W_BOHRUNG-SICHTBAR_12.5" "W_B-S_12.5")
	   (cons "W_BOHRUNG-SICHTBAR_13" "W_B-S_13")
	   (cons "W_BOHRUNG-SICHTBAR_15.2" "W_B-S_15.2")
	   (cons "W_BOHRUNG-SICHTBAR_15.5" "W_B-S_15.5")
	   (cons "W_BOHRUNG-SICHTBAR_17" "W_B-S_17")
	   (cons "W_BOHRUNG-SICHTBAR_3" "W_B-S_3")
	   (cons "W_BOHRUNG-SICHTBAR_3.1" "W_B-S_3.1")
	   (cons "W_BOHRUNG-SICHTBAR_30" "W_B-S_30")
	   (cons "W_BOHRUNG-SICHTBAR_4.2" "W_B-S_4.2")
	   (cons "W_BOHRUNG-SICHTBAR_7_1" "W_B-S_7_1")
	   (cons "W_BOHRUNG-SICHTBAR_8" "W_B-S_8")
	   (cons "W_BOHRUNG-SICHTBAR_8.5" "W_B-S_8.5")
	   (cons "W_BOHRUNG-UNSICHTBAR_11.1" "W_B-US_11.1")
	   (cons "W_BOHRUNG-UNSICHTBAR_12.5" "W_B-US_12.5")
	   (cons "W_BOHRUNG-UNSICHTBAR_14" "W_B-US_14")
	   (cons "W_BOHRUNG-UNSICHTBAR_17" "W_B-US_17")
	   (cons "W_BOHRUNG-UNSICHTBAR_3" "W_B-US_3")
	   (cons "W_BOHRUNG-UNSICHTBAR_3.1" "W_B-US_3.1")
	   (cons "W_BOHRUNG-UNSICHTBAR_30" "W_B-US_30")
	   (cons "W_BOHRUNG-UNSICHTBAR_37" "W_B-US_37")
	   (cons "W_BOHRUNG-UNSICHTBAR_4.2" "W_B-US_4.2")
	   (cons "W_BOHRUNG-UNSICHTBAR_7" "W_B-US_7")
	   (cons "W_BOHRUNG-UNSICHTBAR_8" "W_B-US_8")
	   (cons "W_BOHRUNG-UNSICHTBAR_8.5" "W_B-US_8.5")
	   (cons "0" "262")
;;;                     (cons "STUTZO" "S_STUTZO")
;;;      (cons "STUTZR" "S_STUTZ")
;;;      (cons "STUTZL" "S_STUTZ")
;;;      (cons "ABZWL" "S_ABZW")
;;;      (cons "ABZWR" "S_ABZW")
;;;      (cons "ABZWO" "s_ABZWOB")
	 )
  )
  (foreach ELEMENT BLLIST
    (setq ALT_BL (car ELEMENT)
	  NEU_BL (cdr ELEMENT)
	  SGET	 (ssget "X" (list (cons 0 "INSERT") (cons 2 ALT_BL))) ;_ end ssget
    ) ;_ end setq
    (if	SGET
      (progn (setq SLENG (sslength SGET)
		   INDEX 0
	     ) ;_ end setq
	     (if (= (tblsearch "BLOCK" NEU_BL) NIL)
	       (progn (command "_.insert" NEU_BL "0,0" "1" "" "") ;_ end command
		      (entdel (entlast))
	       ) ;_ end progn
	     ) ;_ end if
	     (while (< INDEX SLENG)
	       (setq SGET_NAME (ssname SGET INDEX)
		     OBJ_DAT   (entget SGET_NAME)
		     OBJ_LAY   (assoc 8 OBJ_DAT)
		     OBJ_NAME  (assoc 2 OBJ_DAT)
		     OBJ_KORD  (assoc 10 OBJ_DAT)
		     OBJ_SC1   (assoc 41 OBJ_DAT)
		     OBJ_SC2   (assoc 42 OBJ_DAT)
		     OBJ_SC3   (assoc 43 OBJ_DAT)
		     OBJ_WINK  (assoc 50 OBJ_DAT)
		     BLCKLIST  (list '(0 . "INSERT")
				     (cons 2 NEU_BL)
				     OBJ_LAY
				     OBJ_KORD
				     OBJ_SC1
				     OBJ_SC2
				     OBJ_SC3
				     OBJ_WINK
			       ) ;_ end list
	       ) ;_ end setq
	       (setq MADE_IT (entmake BLCKLIST))
	       (if (/= MADE_IT NIL)
		 (entdel SGET_NAME)
	       ) ;_ end if
	       (setq INDEX (1+ INDEX))
	     ) ;_ end while
	     (princ (strcat "\n"
			    (itoa INDEX)
			    "x "
			    ALT_BL
			    "durch "
			    NEU_BL
			    "ersetzt!"
		    ) ;_ end strcat
	     ) ;_ end princ
      ) ;_ end progn
      (princ (strcat "\nKein Block: \"" ALT_BL "\" vorhanden!"))
    ) ;_ end if
  ) ;_ end foreach
  (setvar "OSMODE" ALT-OS)
  (setvar "CMDECHO" 1)
  (setvar "FILEDIA" 1)
  (princ)
) ;_ end defun
(princ "\nBlöcke austauschen, Start mit \"BLRED\" !")
(princ)

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