Many thanks,
Wolfhart

Am 21.02.2021 um 04:57 schrieb Wolfhart Totschnig
wolfhart.totschnig@xxxxxxxxxxx:

Thank you, Kurt, Liam, and Michele, for the prompt replies!

Kurt's and Michele's suggestions did not resolve my problem. Installing
the "XML Tree" extension for Chrome did not accelerate the processing of
the XSL stylesheet, and Firefox still refuses to execute the stylesheet
after changing the said security setting.

To Liam's suggestions:

Are you producing XHTML with a DOCTYPE?

No, just HTML (see below).

Without seeing teh stylesheets or the input or the output it's
impossible to say.

I am not sure what a minimal example would be in this case. Here, at any
rate, are the preambles of the XML files and of the stylesheet:

<?xml version="1.0" encoding="UTF-8"?>
<?xml-stylesheet type="text/xsl" href="../zettel.xsl"?>
<zettel xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="../zettel.xsd">

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.1"

For XSLT using 1.1 seems an odd version, I have to say, as that never
was a final W3C recommendation. Not likely, however, to be the cause of
your problem. Does Firefox execute your XSLT if you change version to
1.0 and use the security setting change Michelle posted earlier?

But I think Firefox for local file URIs only allows downwards selection
like `href="zettel.xsl"` or `href="subdir/zettel.xsl"`, not any upwards
navigation like ".." in the file system.