NodeLen in In-situ OAM trace option about ietf HOT 1 OPEN

On (2.): Per the discussion on the IPPM list, text should be added which states that either the short or the long version of a data field is used, but never both at the same time

For reference (quote from the mailing list discussion):

Regardless bit[7], when all bits are set where some are short and some are wide, the current total is 14 where we have spare of 4 bits (12-15). If they will be used this field will not be able to show the total node length

Without considering bit[7], looking at the current bits there should be no need for any combination with length greater than 11.
Why would anyone need both short (4-octets) and wide (8-octets) fields of Hop_Lim and Node_id?
Or both short and wide fields of ingress_if_id and egress_if_id?
Or both short and wide fields of app_data?

Agree that it is not reasonable to use both short and wide, it should be documented to restrict it.
For the other bits that are now reserved 12-15 (4 bits) we could reach to 15 which is the maximum value of this field.
In case one of them will be defined as wide without a short version we will exceed the width of the field.

from ietf.