IF suspect = DeckOfCards [n] AND SuspectState = ALIVE THEN
      Arrest (suspect)
END;
      

string          : ARRAY [0..9] OF CHAR        (* a character string of 10 tokens *)
quarks          : ARRAY [3..7] OF CARDINAL    (* array of cardinals              *)
days            : ARRAY [Mon..Fri] OF Days    (* the workingdays array..         *)
      

FOR  n := 1  TO  99  BY  11  DO .... END;
      

CASE char OF
   '1'        :  Write ('1')              |
   '2'        :  Write ('9')              |
   '3', '4',
   '5', '6'   :  Write ('Z')              |
   ['a'..'z'] :  Write ('-')
ELSE
   Write ('Q')
END;
      

CONST   LF         = 12C;
        CR         = 15C;
	MaxPos     = 120;

VAR     Xpos, Ypos               : CARDINAL;
	str                      : ARRAY [0..63] OF CHAR;

yield := cherries DIV pickers;
DogsPart := cherries MOD pickers;
      

FOR n := 1 TO HIGH (string) DO
    string [n] := CAP (string [n])
END;
    
WHILE n < HIGH (string) DO
   string [n] := CAP (string [n])
   INC (n)
END;
    
WITH House [n] DO
   LivingRoom := 12;
   Toilet := 11;
   Kitchen := 9
END;
      

IF option = 'Home' THEN  Signal (Red)
ELSIF option = 'Work' THEN  Signal (Green)
ELSIF option = 'Out'  THEN  Signal (Yellow)
ELSE
    Signal (Flash)
END;
      

The statement before an END statement does not need a semicolon as a line terminator. You MAY put it there, but it has no function:

IF cherries > 0 THEN
   EachPart := cherries DIV pickers;
   DogsPart := cherries MOD pickers
END;
      

FOR n := 1 TO HIGH (string) DO
   string [n] := CAP (string [n])
END;
      

IF KeyPressed = TRUE THEN
   GetKey (token);
   IF token > 'a' AND token < 'z'
       token := CHR (ORD (token) - 32)
   ELSE
       token := '*'
   END
ELSE
   Write (ASCII.BEL)
END;
      

On commercial systems, when a company sells libraries, it can suffice to sell the DEFINITION MODULE and the object file which was made by compiling the IMPLEMENTATION MODULE. Doing so, the company can sell their products without having nosy geeks trying to steal their code.
In the GPL time, this commercial part is less important. But the code hiding features remain important when groups of programmers work on a combined project and none may rely on the others code. This last, to prevent the whole program from collapsing as a result of one altered line in someone else's source...

FROM  InOut   IMPORT  Write, WriteLn, WriteCard;
    
IMPORT ASCII;
IMPORT Terminal;
      

The second way of importing functions (or properties) can be handy if you need to use two entities of the same name, but from different DEFINITION MODULES. Here's an example, relying on the above IMPORT's:

WriteCard (number, 6);
Write (ASCII.LF);
IF number < 230 THEN  Terminal.Write ('#')  END;
      

IF 23 IN BITSET (flagword) THEN  Signal (SigSegv)  END;
      

LOOP
    GetKey (token);
    IF token = ASCII.LF THEN  EXIT  END;
    IF n <= HIGH (string) THEN
	string [n] := token;
	INC (n)
    END
END;
      

IF NOT (Sky = Blue) THEN Get (umbrella) END;
      

IF  I = mad OR U = mad THEN
    WriteString ('At least one of us is mad.')
ELSE
    WriteString ('We're both sane.')
END;
      

PROCEDURE  WriteString (string  : ARRAY OF CHAR);
    
VAR   i      : CARDINAL;
    
BEGIN
    i := 0;
    LOOP
        IF  i > HIGH (string)  THEN  EXIT  END;
	IF string [i] = 0C THEN
	    EXIT
	END;
	Write (string [i]);
	INC (i)
    END
END WriteString;
      

TYPE   DoorStatus   = (Open, Close, Out);
       Temperatures = RECORD
                        RoomNr    : CARDINAL;
			RoomTemp  : INTEGER;
			Doors     : DoorStatus
		      END;

VAR    TempTrack    : ARRAY [0..31] OF Temperatures

WITH TempTrack [n] DO
     RoomNr   := InPort (LabelScanner);
     RoomTemp := ReadADC (RoomNr);
     Doors    := CheckDoor (RoomNr)
END;
      

REPEAT
    WriteCard (temps [i], 5);
    INC (i);
UNTIL i > HIGH (temps);
      

PROCEDURE GetTemperature (nr : CARDINAL) : REAL;
    
VAR   temp         : REAL;
    
BEGIN
   temp := ReadAdc (nr);
   RETURN temp
END GetTemperature;
      

MODULE TryMe;

VAR    Me       : CARDINAL;

PROCEDURE Try (VAR x   : CARDINAL);

VAR  local           : REAL;

BEGIN
    local := <something>;
END Try;

BEGIN
    Try (Me)
END TryMe.
      

WHILE n # 12 DO
    something ();
    INC (n)
END;
      

PROCEDURE ABS (VAR x : INTEGER);

BEGIN
    IF x < 0 THEN 
        x := -x
    END
END ABS;      
      

PROCEDURE CAP (VAR ch   : CHAR);
    
BEGIN
    IF ch > 'a' AND ch < 'z' THEN
	ch := CHR (ORD (ch) - 32)
    END
END CAP;
      

VAR    Celsius    : REAL;
       Fahrenheit : INTEGER;

Celsius := (FLOAT (Fahrenheit) - 32.0) / 1.8;
Fahrenheit := TRUNC (Celsius * 1.8) + 32;
      

PROCEDURE ODD (x : CARDINAL) : BOOLEAN;

BEGIN
    IF x MOD 2 = 0 THEN
	RETURN FALSE
    ELSE
	RETURN TRUE
    END
END ODD;
      

TYPE   DaySet = (Mon, Tue, Wed, Thu, Fri, Sat, Sun);
       ChrSet = [A..Z];

VAR    chrvar               : ChrSet;
       day                  : DaySet;
       char                 : CHAR;

chrvar := 'C';		(* ORD (chrvar) now is 2  *)
   day := Sun;		(* ORD (day) is 6         *)
  char := 'P';		(* ORD (char) = 80        *)
      

TYPE   DaySet = (Mon, Tue, Wed, Thu, Fri, Sat, Sun);
       ChrSet = [A..Z];
	   
VAR    chrvar               : ChrSet;
       day                  : DaySet;
       char                 : CHAR;

chrvar := VAL (ChrSet, 2);    (* chrvar now is C        *)
day := VAL (DaySet, 5);       (* day now is Sat         *)
      

DEC (n)              equals    n := n - 1;
DEC (n, 4)           equals    n := n - 4;
DEC (n, Counts [i])  equals    n := n - Counts [i];
      

INC (n)              equals    n := n + 1;
INC (n, 4)           equals    n := n + 4;
INC (n, Counts [i])  equals    n := n + Counts [i];
      

It will be clear that BITSET is typical low level function.

IF n IN BITSET (statusword) THEN ... some action ... END;
      

quotient  := 16 DIV 3;      (* quotient  = 3 *)
remainder := 16 MOD 3;      (* remainder = 1 *)
      

IF a = 12 THEN ... END;  (*  if a is 12 then ... *)
      

1 < 2    is TRUE
2 < 1    is FALSE
      

1 <= 2    is TRUE
1 <= 1    is TRUE
2 <= 1    is FALSE
      

1 > 2    is FALSE
2 > 1    is TRUE
      

1 >= 2    is FALSE
2 >= 2    is TRUE
2 >= 1    is TRUE
      

IF  1  IN  BITSET (2)  THEN
   WriteString ('Bit 1 was set.')
ELSE
   WriteString ('Bit 1 was cleared.')
END