An assignment statement uses  an  assignment  operator  (:=)  to
  assign a value to a variable or function identifier.

  Syntax:

     variable-access := expression

  The 'variable-access' is an identifier, array component,  record
  component, pointer dereference, or file buffer.

  The  'expression'  is  a  run-time  expression  whose  type   is
  assignment  compatible with the type of the variable.  The value
  of the expression is the value assigned to the variable.