Allowed chars

Implicitly if not in prolog indicated otherwise, eg.

<?xml version="1.0" encoding="Windows-1250"?>

UTF-8 or UTF-16 is used.

The distinction between UTF-8 and UTF-16 is done according to the first two bytes of the document entity (ie. file), by so-called byte-order-mark xFFFE.

If not present, UTF-8 is assumed, thus UTF-8 is the implicit encoding of UNICODE in XML.