From Saxon 12.2, with HTML5 serialization, if indentation is on, a newline is added after the DOCTYPE declaration.

From Saxon 12.3, a new serialization parameter escape-solidus is available. The XSLT and XQuery syntax for this requires 4.0 to be available, but it can be used in API calls and from the command line without enabling 4.0. The default is yes; if the parameter is set to no, the JSON serialization method outputs "/" as "/", not as "\/".