Add Examples, apply rfc3209 style for ERO encoding
Add Motivation, Rationale and Applicability' section.
rework intro and MPLS Label TLV header

add link to IS-IS TE
change address to prefix
add link for domain-wide flags
add subTLV handling procedures
rework the examples section
shrink label header to only use 3 octets
add a node about sequential advertisements of TLVs
rework intro
complete the 4-path interarea example
add "lack of path" notion to "Motivation" section
fix typos
Add Inter-Area Protocol Procedures and Prefix ERO path semantics