Public vs System Identifiers

[Crazy]

Hi all,

When using a public identifier (FPI) you may specify a URI to the DTD if the processor cannot resolve the public identifier. With system identifiers you always specify a URI. So my question is why use a public identifier with a URI, when you can simply use a system identifier? I mean what are the benefits of using a public identifier over a system identifier in such cases?

Cheers

[Robert Wellock]

Basically how I see it is it's similar to having relative and absolute links; thus when your eXtensible Markup Language (XML) file moves you can still reference one unique specific data location.