begin comment record RPerson as example of reference to the same record; record RDate (integer month, day, year); record RPerson (string name, lastname; reference (RDate) birth; string (1) sex; reference (RPerson) father, mother); procedure PersonWrite(reference(RPerson) value pers); begin writeon( name(pers), lastname(pers) ); end; reference(RPerson) adam, eve, abel; adam := RPerson("Adam", " ", RDate(1,1, -7500), "m", null, null); eve := RPerson("Adam", " ", RDate(1,1, -7500), "f", null, null); abel := RPerson("Abel", "son of Adam ", RDate(1,1, -7400), "m", adam, eve); PersonWrite(abel); end.