+# TODO: DocBook doesn't support several letters in the same file.
+# DocBook design note: there are several ways to implement sender data, this class does it in
+# another way that the other letters. Usually, there is a large <address> tag with author
+# information in <info>, but there is no possibility to include a URL in this case.
+# Therefore, here, we use a <author> in <info>, having an <address>. <author> allows a URL
+# (<uri>) and an address. However, phone and fax numbers should be put in <address>, they
+# are not allowed directly in <author>... The generated DocBook will not be valid due to this!
+
+Format 103