[xml] What's the meaning of returning -1 from htmlParseChunk?

[Auguste Pop <auguste gmail com>]

I am new in using libxml and am trying to use this library to parse
real world HTML files.

According to the documentation, the function htmlParseChunk returns
"zero if no error, the xmlParseErrors otherwise". However, -1 is not
listed in the xmlParserErrors enum type. I am just wandering what's
the meaning of that?

It seems that after a return value of -1, all subsequent chunks are
simply ignored.

Sorry for my poor English and thank you for your kind attention.