examples type complex record reimreal end type date record daymonthyearinteger end type person record namefirstnamenamebirthdatedatemaleboolean end we may visualize particularrecord-structured values offor examplethe variables zcomplex ddate pperson as shown in fig complex date person smith - john true fig records of type complexdate and person the identifiers sn introduced by record type definition are the names given to the individual components of variables of that type as components of records are called fieldsthe names are field identifiers they are used in record selectors applied to record structured variables given variable xt its -th field is denoted by si selective updating of is achieved by using the same selector denotation on the left side in an assignment statementx si : where is value (expressionof type givenfor examplethe record variables zdand declared abovethe following are selectors of componentsz im (of type reald month (of type integerp name (of type namep birthdate (of type datep birthdate day (of type integerp mail (of type booleanthe example of the type person shows that constituent of record type may itself be structured thusselectors may be concatenated naturallydifferent structuring types may also be used in nested fashion for examplethe -th component of an array being component of record variable is denoted by [ ]and the component with the selector name of the -th record structured component of the array is denoted by [is it is characteristic of the cartesian product that it contains all combinations of elements of the constituent types but it must be noted that in practical applications not all of them may be meaningful for instancethe type date as defined above includes the st april as well as the th february which are both dates that never occurred thusthe definition of this type does not mirror the actual situation