Draft: roll-useofrplinfo

Commentary: This covers the text from the beginning up to Section 7.2.1 . These were reviewed with  on March 26th . I will continue my review from Section 7.2.2 forward . More trivial editorial suggestions to follow , as well . 
 Many thanks for these fixs .
Flag Day: A transition that involves having a network with different
values of RPI Option Type.  Thus the network does not work correctly
(Lack of interoperation).
Flag Day: In this document, refers to a transition that involves
having a network with different values of RPI Option Type.
A RUL is a special case of external target when the target is
actually a host and it is known to support a consumed Routing Header
and to ignore a HbH header as prescribed by RFC8200.  The target may
have been learned through as a host route or may have been registered
to the 6LR using RFC8505.
A RUL is a special case of external target when the target is
actually a host and it is known to support a consumed Routing Header
and to ignore a HbH header as prescribed by RFC8200.  The target may
have been learned through an external routing protocol or may have
been registered to the 6LR using RFC8505.
The leaves marked as RUL (G and J) are devices which do not speak RPL
at all (not-RPL-aware), but uses Router-Advertisements, 6LowPAN DAR/
DAC and efficient-ND only to participate in the network RFC6775.  In
the document these leaves (G and J) are also referred to as an IPv6
node.
The leaves marked as RUL (G and J) are devices which do not speak RPL
at all (not-RPL-aware), but uses Router-Advertisements, 6LowPAN DAR/
DAC and 6LoWPAN ND only to participate in the network RFC8505.  In
the document these leaves (G and J) are also referred to as an IPv6
node.
A corollary is that an RH3 or RPL Option can only be removed by an
intermediate router if it is placed in an encapsulating IPv6 Header,
which is addressed TO the intermediate router.  When it does so, the
whole encapsulating header must be removed.  (A replacement may be
added).  This sometimes can result in outer IP headers being
addressed to the next hop router using link-local address.
A corollary is that an intermediate router can remove an RH3 or RPL
Option only if it is placed in an encapsulating IPv6 Header that is
addressed TO this intermediate router.  When doing the above, the
whole encapsulating header must be removed.  (A replacement may be
added).  This sometimes can result in outer IP headers being
addressed to the next hop router using link-local address.
The earlier examples are more extensive to make sure that the process
is clear, while later examples are more concise.
Throughout the following subsections, the examples are described in
more details in the first subsections, and more concisely in the
later ones.
In cases where no IPv6-in-IPv6 header is needed, the column states as
"No".  If the IPv6-in-IPv6 header is needed, the column shows "must".
In all cases, the RPI is needed, since it identifies inconsistencies
(loops) in the routing topology.  In general, the RH3 is not needed
because it is not used in storing mode.  However, there is one
scenario (from the root to the RUL in SM) where the RH3 can be used
to indicate the RUL (Storing-root2notrplnoIPIP).
In cases where no IPv6-in-IPv6 header is needed, the column states
"No", and the destination is N/A (Not Applicable).  If the IPv6-in-
IPv6 header is needed, the column shows "must".
In all cases, the RPI is needed, since it identifies inconsistencies
(loops) in the routing topology.  In general, the RH3 is not needed
because it is not used in storing mode.  However, there is one
scenario (from the root to the RUL in SM) where the RH3 can be used
to point at the RUL (Storing-root2notrplnoIPIP).
The 6LBR will insert an RPI, encapsulated in a IPv6-in-IPv6 header.
The IPv6-in-IPv6 header is addressed to the 6LR parent of the RUL
(6LR_n).  The 6LR parent of the RUL removes the header and sends the
packet to the RUL.
The 6LBR will encapsulate the packet in an IPv6-in-IPv6 header, and
prepend an RPI.  The IPv6-in-IPv6 header is addressed to the 6LR
parent of the RUL (6LR_n).  The 6LR parent of the RUL removes the
header and sends the packet to the RUL.
When the packet arrives from IPv6 node (Node G) to 6LR_1 (Node E),
the 6LR_1 will insert an RPI, encapsulated in a IPv6-in-IPv6 header.
The IPv6-in-IPv6 header is addressed to the root (Node A).  The root
removes the header and processes the packet.
When the packet arrives from IPv6 node (Node G) to 6LR_1 (Node E),
the 6LR_1 will insert encapsulate the packet in an IPv6-in-IPv6
header and prepend an RPI.  The IPv6-in-IPv6 header is addressed to
the root (Node A).  The root removes the header and processes the
packet.
No IPv6-in-IPv6 header is required.