====== Package STANDARD ======
<code vhdl>
PACKAGE STANDARD IS

-- predefined enumeration types:
TYPE severity_level IS ( note, warning, error, failure ) ;
TYPE boolean IS ( false, true ) ;
TYPE bit IS ( '0', '1' ) ;
TYPE character IS ( NUL, SOH, STX, ETX, EOT, ENQ, ACK, BEL, BS, HT, LF, VT,
FF, CR, SO, SI, DLE, DC1, DC2, DC3, DC4, NAK, SYN, ETB, CAN, EM, SUB, ESC,
FSP, GSP, RSP, USP, ' ', '!', '"', '#', '$', '%', '&', ''', '(', ')', '*',
'+', ',', '-', '.', '/', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
':', ';', '<', '=', '>', '?', '@','A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I',
'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
'Y', 'Z',' '[', '\', ']', '^', '_', '`', 'a', 'b', 'c', 'd', 'e', 'f', 'g',
'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
'w', 'x', 'y', 'z',' '{', '|', '}', '~', DEL, C128, C129, C130, C131, C132,
C133, C134, C135, C136, C137, C138, C139, C140, C141, C142, C143, C144, C145,
C146, C147, C148, C149, C150, C151, C152, C153, C154, C155, C156, C157, C158,
C159, ' ', '¡', '¢', '£', '¤', '¥', '¦', '§', '¨', '©', 'ª', '«', '¬', '',
'®', '¯', '°', '±', '²', '³','´', 'µ', '¶', '·', '¸', '¹', 'º', '»', '¼', '½',
'¾', '¿', 'À', 'Á', 'Â', 'Ã', 'Ä', 'Å', 'Æ', 'Ç', 'È', 'É', 'Ê', 'Ì', 'Í',
'Î', 'Ï', 'Ð', 'Ñ', 'Ò', 'Ó', 'Ô', 'Õ', 'Ö', '×', 'Ø', 'Ù', 'Ú', 'Û', 'Ü',
'Ý', 'Þ', 'ß', 'à', 'á', 'â', 'ã', 'ä', 'å', 'æ', 'ç', 'è', 'é','ê', 'ì', 'í',
'î', 'ï', 'ð', 'ñ', 'ò', 'ó', 'ô', 'õ', 'ö', '÷', 'ø', 'ù', 'ú', 'û', 'ü',
'ý', 'þ', 'ÿ');

-- predefined numeric types :
TYPE integer IS RANGE implementation_defined ;
TYPE real IS RANGE implementation_defined ;

-- predefined type time :
TYPE time IS RANGE implementation_defined
   UNITS
     fs ; --Femtosekunde
     ps = 1000 fs ; --Picosekunde
     ns = 1000 ps ; --Nanosekunde
     us = 1000 ns ; --Microsekunde
     ms = 1000 us ; --Millisekunde
     sec = 1000 ms ; --Sekunde
     min = 60 sec ; --Minute
     hr = 60 min ; --Stunde
   END UNITS ;
SUBTYPE delay_length IS time RANGE 0 fs TO TIME'HIGH ;

-- function that returns the current simulation time :
IMPURE FUNCTION now RETURN delay_length ;

-- predefined numeric subtypes :
SUBTYPE natural IS integer RANGE 0 TO integer'high ;
SUBTYPE positive IS integer RANGE 1 TO integer'high ;

-- predefined array types :
TYPE string IS ARRAY ( positive RANGE <> ) OF character ;
TYPE bit_vector IS ARRAY ( natural RANGE <> ) OF bit ;

-- predefined types for opening files :
TYPE file_open_kind IS ( READ_MODE , WRITE_MODE , APPEND_MODE ) ;
TYPE file_open_status IS ( OPEN_OK , STATUS_ERROR , NAME_ERROR , MODE_ERROR ) ;

-- the `foreign attribute:
ATTRIBUTE foreign: string ;
END STANDARD ;
</code>