The Journal - a proposed syslog replacement

The problem with XML is:
1) a syntax originally designed for marking up documents got reused for
data, with the result that XML provides distinctions which are
unnecessary for data purposes (e.g. element vs. attribute distinction)
2) historical baggage, e.g. DTDs
Certainly you can define new syntaxes which avoid those two problems that
XML has. On the other hand, whatever its warts, XML is an industry standard,
and practical considerations often imply choosing the imperfect industry
standard over some technically superior but rarely used alternative.

But, JSON is quite common now, and addresses some of the issues above. (But
I think it has its own deficiencies too)