<!-- #directive attr1="value1" attr2="value2" ... -->
Directives are enclosed in standard HTML comments. So if XSSI processing is not enabled, your browser will ignore them. Otherwise, each directive is evaluated and replaced by its results.
Note: Enclosing an attribute's value in double quotes is not mandatory if it does not contain whitespaces or references to variables.
Note: A whitespace should precede the comment terminator -->.