The list of external document content URLs that are not allowed to be loaded by the readerengine after loading a document.

The file itself contains a list of (newline separated) regular expressions. Each external URL is first checked against the list of blacklist URL regular expressions. If the external URL matches one blacklist entry, the external URL is then checked against the list of whitelist URL regular expressions.

The behavior in summary is as follows:
If the URL is not blacklisted and not whitelisted, it is resolved at runtime.
If the URL is blacklisted but not whitelisted, it is not resolved at runtime.
If the URL is not blacklisted but whitelisted, it is resolved at runtime.
If the URL is blacklisted and whitelisted, it is resolved at runtime.
In boolean notation: valid = (!blacklisted) || whitelisted

Please note that the regular expressions need to fully qualify the patterns that the URL should be checked against.
Upper/Lower cases need to be handled by the regular expression as well.
The file itself needs to be UTF-8 encoded to be read appropriately.

Default value: /opt/open-xchange/etc/readerengine.blacklist