The document is generally fine, with the following offered as a suggestion for clarity:

Page 10 should be updated with the text in braces []:

Otherwise, when a node receives an ICMPv4 Extended Echo Request, it
   MUST format [the IPv4 header of] an ICMP Extended Echo Reply as follows:
   *  Don't Fragment (DF) flag is 1
   *  More Fragments flag is 0
   *  Fragment Offset is 0
  [(the above indicate that the packet is not source fragmented and must not be on-path fragmented)]
   *  TTL is 255
   *  Protocol is ICMP
   When a node receives an ICMPv6 Extended Echo Request, it MUST format
   [the IPv6 header of] an ICMPv6 Extended Echo Reply as follows:
   *  Hop Limit is 255
   *  Next Header is ICMPv6
  [* No use of the IPv6 Fragmentation Header (i.e., not source fragmented)]