+##### Locale::Po4a::Xhtml
+
+* does not run any external program
+* does not build regexp's from untrusted variables
+
+=> Seems safe as far as the `includessi` option is disabled; the po
+plugin explicitly disables it.
+
+Relies on Locale::Po4a::Xml` to do most of the work.
+
+##### Locale::Po4a::Xml
+
+* does not run any external program
+* the `includeexternal` option makes it able to read external files;
+ the po plugin explicitly disables it
+* untrusted variables are escaped when used to build regexp's
+