PROCEDURE BLOCK(*FSYS: SETOFSYS*);
 LABEL 1;
 VAR BFSYFOUND: BOOLEAN;

   PROCEDURE FINDFORW(FCP: CTP);
     BEGIN
       IF FCP <> NIL THEN
         WITH FCP^ DO
           BEGIN
             IF KLASS IN [PROC,FUNC] THEN
               IF PFDECKIND = DECLARED THEN
                 IF PFKIND = ACTUAL THEN
                   IF FORWDECL THEN
                     BEGIN
                       USERINFO.ERRNUM := 117; WRITELN(OUTPUT);
                       WRITE(OUTPUT,NAME,' undefined')
                     END;
             FINDFORW(RLINK); FINDFORW(LLINK)
           END
     END (*FINDFORW*) ;

   BEGIN (*BLOCK*)
      IF (NOSWAP) AND (STARTINGUP) THEN
        BEGIN
          BODYPART(FSYS,NIL);
          EXIT(BLOCK);
        END;
      IF (SY IN [UNITSY,SEPARATSY]) AND (NOT INMODULE) THEN
        BEGIN
          UNITPART(FSYS + [UNITSY,INTERSY,IMPLESY,ENDSY]);
          IF SY = PERIOD THEN EXIT(BLOCK)
        END;
      NEWBLOCK:=TRUE;
      REPEAT
        IF NOT NEWBLOCK THEN
          BEGIN
            DP := FALSE; STMTLEV := 0; IC := 0; LINEINFO := 0;
            IF (NOT SYSCOMP) OR (LEVEL>1) THEN FINDFORW(DISPLAY[TOP].FNAME);
            IF INMODULE THEN
              IF TOS^.PREVLEXSTACKP^.DFPROCP = OUTERBLOCK THEN
                IF (SY = ENDSY) THEN
                  BEGIN FINISHSEG; EXIT(BLOCK) END
                ELSE IF (SY = BEGINSY) THEN
                  BEGIN ERROR(13); FINISHSEG; EXIT(BLOCK) END;
            IF SY = BEGINSY THEN INSYMBOL ELSE ERROR(17);
            REPEAT
              BODYPART(FSYS + [CASESY] - [ENDSY], TOS^.DFPROCP);
              BFSYFOUND := (SY = TOS^.BFSY) OR (INMODULE AND (SY = ENDSY));
              IF NOT BFSYFOUND THEN
                BEGIN
                  IF TOS^.BFSY = SEMICOLON THEN
                    ERROR(14)  (*SEMICOLON EXPECTED*)
                  ELSE  ERROR(6);  (* PERIOD EXPECTED *)
                  SKIP(FSYS + [TOS^.BFSY]);
                  BFSYFOUND := (SY = TOS^.BFSY) OR (INMODULE AND (SY = ENDSY))
              END
            UNTIL (BFSYFOUND) OR (SY IN BLOCKBEGSYS);
            IF NOT BFSYFOUND THEN
              BEGIN
                IF TOS^.BFSY = SEMICOLON THEN ERROR(14)
                ELSE ERROR(6); (*PERIOD EXPECTED*)
                DECLARATIONPART(FSYS);
              END
            ELSE
              BEGIN
                IF SY = SEMICOLON THEN INSYMBOL;
                IF (NOT(SY IN [BEGINSY,PROCSY,FUNCSY,PROGSY])) AND
                   (TOS^.BFSY = SEMICOLON) THEN
                  IF NOT (INMODULE AND (SY = ENDSY)) THEN
                    BEGIN
                      ERROR(6); SKIP(FSYS);
                      DECLARATIONPART(FSYS);
                    END
                  ELSE GOTO 1
                ELSE
          1:      BEGIN
                    WITH TOS^ DO
                      BEGIN
                        IF DFPROCP <> NIL THEN
                          DFPROCP^.INSCOPE:=FALSE;
                        IF ISSEGMENT THEN
                          BEGIN
                            IF CODEINSEG THEN FINISHSEG;
                            IF DLINKERINFO AND (LEVEL = 1) THEN
                              BEGIN SEGTABLE[SEG].SEGKIND := 2;
                                WRITELINKERINFO(TRUE)
                              END
                            ELSE
                              IF CLINKERINFO THEN
                                BEGIN SEGTABLE[SEG].SEGKIND := 2;
                                  WRITELINKERINFO(FALSE)
                                END;
                            NEXTPROC:=SOLDPROC;
                            SEG:=DOLDSEG;
                          END;
                        LEVEL:=DOLDLEV;
                        TOP:=DOLDTOP;
                        LC:=DLLC;
                        CURPROC:=POLDPROC;
                      END;
                    RELEASE(TOS^.DMARKP);
                    TOS:=TOS^.PREVLEXSTACKP;
                    NEWBLOCK:=(SY IN [PROCSY,FUNCSY,PROGSY]);
                  END
              END
          END
        ELSE
          BEGIN DECLARATIONPART(FSYS);
            IF LEVEL = 0 THEN
              IF SY IN [UNITSY,SEPARATSY] THEN
                BEGIN
                  UNITPART(FSYS + [UNITSY,INTERSY,IMPLESY,ENDSY]);
                  IF SY IN [PROCSY,FUNCSY,PROGSY] THEN DECLARATIONPART(FSYS)
                END
          END;
      UNTIL TOS = NIL;
      FINISHSEG;
  END (*BLOCK*) ;