Pascal Report  159  The component type of a file type must be an assignable type (see  Section 6.5). A file that is in  inspection  mode may be positioned at any  component of the sequence or at the  end-oJ-Jile  position. A file that is  in  generation  mode is always positioned at end-of-file. File values are  manipulated by predeclared file-handling procedures and functions  (see Section 11).  The predefined structured type identifier  Text  represents a special  file type in which the sequence is structured as zero or more  lines.  A line  consists of zero or more characters (values oftype Char) followed by a  special  end-oj-line  marker. A variable of type Text is called a  textfile.  If  a nonempty textfile is  in  inspection mode then there is always an  end-of-line immediately preceding the end-of-file position. There are  several  additional  predeclared  procedures  and  functions  for  manipulating textfiles (see Sections 11.5 and 12). An implementation­ defined set of characters may be prohibited from textfiles, and writing  any of these characters to a textfile is implementation-dependent.  A pointer type is distinguished from the structured and simple types in  that its set of values is  dynamic;  i.e., values of a pointer type are created  and destroyed during program execution. The set of values of a pointer  type always contains a special value, represented by  nil.  Every other  value in the set must be created by a program using the predeclared  procedure  New  (see Section 11.4.2); such values are called identifying  values  because each one identifies a variable, the so-called  identified  variahle  (see Section 7.3). An identified variable possesses the  domain  type  of the pointer type. An identifying value and its identified variable  can be destroyed using the  predeclared procedure  Dispose  (see  Section 11.4.2). All identifying values created by a program cease to  exist when the program terminates.  6.3.  Pointer Types  6.4.  Example of a Type Definition Part  type  Natural  =  o .. Maxint;  Color  =  (Red,  Yellow,  Green,  Blue);  PointerType  =  "i"  DomainType  I  PointerTypeldentiJier .  DomainType  =  Typeldent~fler  .  PointerTypeldentiJier  =  TypeldentifJer . 