os << "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"
if (output_preamble) {
os << "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"
- << "<!DOCTYPE html PUBLIC \"-//W3C//DTD XHTML 1.1 plus MathML 2.0//EN\" \"http://www.w3.org/TR/MathML2/dtd/xhtml-math11-f.dtd\">\n"
+ << "<!DOCTYPE html PUBLIC \"-//W3C//DTD XHTML 1.1 plus MathML 2.0//EN\" \"http://www.w3.org/TR/2001/REC-MathML2-20010221/dtd/xhtml-math11-f.dtd\">\n"