cam has changed single to double quotes in the beginning of xml-guide rev 1.41. However, he/she missed another couple of such quotes: <?xml version='1.0' encoding='UTF-8'?> <!DOCTYPE book SYSTEM "/dtd/book.dtd"> <?xml version='1.0' encoding='UTF-8'?> <!DOCTYPE sections SYSTEM "/dtd/book.dtd"> I think double quotes fit those, too. Reproducible: Always Steps to Reproduce: 1. 2. 3.
Using single or double quotes does not matter.