+This is then followed by the GVariant fields array ("a{tv}"), and
+finally the actual body as variant (v). Putting this altogether a
+packet on dbus2 hence qualifies as a fully compliant GVariant
+structure of (yyyyuta{tv}v).
+
+For details on gvariant, see:
+
+https://people.gnome.org/~desrt/gvariant-serialisation.pdf
+
+Regarding the framing of dbus2, also see:
+
+https://wiki.gnome.org/Projects/GLib/GDBus/Version2
+
+The first four bytes of the header are defined the same way for dbus1
+and dbus2. The first bytes contain the endianess field and the
+protocol version, so that the remainder of the message can be safely
+made sense of just by looking at the first 32bit.
+
+Note that the length of the body is no longer included in the header
+on dbus2! In fact, the message size must be known in advance, from the
+underlying transport in order to parse dbus2 messages, while it is
+directly included in dbus1 message headers. This change of semantics
+is an effect of GVariant's basic design.
+
+The serial number has been renamed cookie and has been extended from
+32bit to 64bit. It is recommended to avoid the higher 32bit of the
+cookie field though, to simplify compatibility with dbus1 peers. Note
+that not only the cookie/serial field in the fixed header, but also
+the reply_cookie/reply_serial additional header field has been
+increased from 32bit to 64bit, too!
+
+The header field identifiers have been extended from 8bit to
+64bit. This has been done to simplify things (as kdbus otherwise uses
+exclusively 64bit types, unless there is a strong reason not to), and
+has no effect on the serialization size, as due to alignment for each
+8bit header field identifier 56 bits of padding had to be added.
+
+Note that the header size changed, due to these changes. However,
+consider that on dbus1 the beginning of the fields array contains the
+32bit array size (since that is how arrays are encoded on dbus1),
+thus, if one considers that size part of the header, instead of the
+array, the size of the header on dbus1 and dbus2 stays identical, at
+16 bytes.