66  Pascal User Manual  To  take a simple example,  assume we  wish to  compute with  complex numbers of the form  a ;  ::1 i, where a and b are real numbers  and  i  is the square root of -1. Thl're is no predefined type "complex."  However, we can easily define  il  record type to represent complex  numbers. This record would need  two fields, both oftype Real, for the  real and imaginary parts. The Syll  tax  necessary to express this is:  Figure 7.b  Syntax diagram for  FieldList  Figure 7.a  Syntax dIagram for  RecordType  Figure 7.c  Syntax diagram for  FixedPart  Figure 7.d  Syntax  dia~!ram  for  RecordSection  r~I----:::Jr--- ~  Fie/dList  II----~- ~---------------------.-------------------~  -E--~  FixedPart  )----..c--------- .--------"7"' _____ ----------'7+_  (  ~I---""",,-------.  CD}------------+l-~f----