On 07.10.2013 19:29, silvioprog wrote: > Hello, > > I was surfing the internet and came across this structure Delphi: > > > TJSONPair= class sealed(TJSONAncestor) > > > So, what is this? Simple: You are not allowed to create child classes of sealed classes (the compiler enforces this). FPC supports this since 2.4.2. Regards, Sven