javaranch mock question

[jim yin]

Which of the following code is valid?

a) <!DOCTYPE SYSTEM SYSTEM "test.dtd">
<SYSTEM></SYSTEM>
b) <!DOCTYPE PUBLIC SYSTEM "test.dtd">
<PUBLIC></PUBLIC>
c) <!DOCTYPE PUBLIC PUBLIC "test.dtd">
<PUBLIC></PUBLIC>
d) <!DOCTYPE SYSTEM PUBLIC "test.dtd">
<PUBLIC></PUBLIC>
Answer : a b

Can PUBLIC and SYSTEM be elements names? Why a and b are correct, not c and d?

[Jayadev Pulaparty]

I guess any name is valid as long as it is a valid xml name (w.r.t the characters it can contain)
The reason why c and d are not correct is that there is nothing like PUBLIC keyword for referring to an external DTD to the best of my knowledge.
Anyone please correct for any mistakes here.
Thanks.

[jim yin]

I think I got it, this is from PXML2:

The use of PUBLIC identifiers should probably be limited to internal systems and SGML legacy applications.

PUBLIC cannot be used to refer to external DTDs.

[Valentin Crettaz]

jim,
it would help if you could write a descriptive subject for the new topic you create, so that people have an idea of what your question is all about. Thank you