<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE language SYSTEM "language.dtd"
[
    <!-- comment line 1
         comment line 2 -->
    <!ENTITY name    "(?![0-9])[\w_:][\w.:_-]*">
    <!ENTITY entref  "&amp;(#[0-9]+|#[xX][0-9A-Fa-f]+|&name;);">
]>
<element attr1="a1" attr2="2.03" attr3="&entity;">
    <sub-element/>
</element>

<wrong<very wrong>>