Index  Abs, 18,20, 192,204,211  Absolute value,  see  Abs  Abstraction, 14  Action, concept of, 1,28, 143  Activation  and formal parameters, 185  point, 172, 181, 187  Activations, 172, 177, 179-180  Active variant, of record, 70, 100,  158,191  Actual  functional parameter, 122, 124,  188  parameter, 107-109, 111-113,  147, 175, 180, 185, 186-187  EBNF for, 187,219,225  lists, 106, 107,  170, 186-188  EBNF for, 187,219,225  syntax diagram for, 107, 234  procedural parameter, 117, 121,  188  value conformant-array parameter,  113, 187  value parameter, 110, 187  variable parameter, 110, 154,  175,187  \dding operators,  EBNF for, 165,218,225  operands of, 165  and precedence, 32,166  (see also  Arithmetic operators)  \ddresses, for pointer types, 94  \lgoI60, vii, 6, 7, 8,142-143  Algol-W, vii  \lgorithm, 1, 179  I\ltemative representations,  of symbols, 10, 148,212  
d. 16, 168,208,212  (see also  Boolean operators)  \postrophe, how to represent, 18,  150  Irahic to Roman, program for,  -+4--46  'rL'Tan, 20, 193,204,211  . ,rL'langent,  see  ArcTan  \rgument.  see  Parameter  . ,rithmetic  funL'tions. predeclared, 192-193  IJperations. on Boolean values, 8  llperators, 17, 146, 167, 208  :  ~  rray  ,'llmponents of, 144, 156  254 