target = "https://www.rfc-editor.org/rfc/rfc9000#section-17.1"

# 17.1.  Packet Number Encoding and Decoding
#
# Packet numbers are integers in the range 0 to 2^62-1 (Section 12.3).
# When present in long or short packet headers, they are encoded in 1
# to 4 bytes.  The number of bits required to represent the packet
# number is reduced by including only the least significant bits of the
# packet number.
# 
# The encoded packet number is protected as described in Section 5.4 of
# [QUIC-TLS].
# 
# Prior to receiving an acknowledgment for a packet number space, the
# full packet number MUST be included; it is not to be truncated, as
# described below.
# 
# After an acknowledgment is received for a packet number space, the
# sender MUST use a packet number size able to represent more than
# twice as large a range as the difference between the largest
# acknowledged packet number and the packet number being sent.  A peer
# receiving the packet will then correctly decode the packet number,
# unless the packet is delayed in transit such that it arrives after
# many higher-numbered packets have been received.  An endpoint SHOULD
# use a large enough packet number encoding to allow the packet number
# to be recovered even if the packet arrives after packets that are
# sent afterwards.
# 
# As a result, the size of the packet number encoding is at least one
# bit more than the base-2 logarithm of the number of contiguous
# unacknowledged packet numbers, including the new packet.  Pseudocode
# and an example for packet number encoding can be found in
# Appendix A.2.
# 
# At a receiver, protection of the packet number is removed prior to
# recovering the full packet number.  The full packet number is then
# reconstructed based on the number of significant bits present, the
# value of those bits, and the largest packet number received in a
# successfully authenticated packet.  Recovering the full packet number
# is necessary to successfully complete the removal of packet
# protection.
# 
# Once header protection is removed, the packet number is decoded by
# finding the packet number value that is closest to the next expected
# packet.  The next expected packet is the highest received packet
# number plus one.  Pseudocode and an example for packet number
# decoding can be found in Appendix A.3.

[[spec]]
level = "MUST"
quote = '''
Prior to receiving an acknowledgment for a packet number space, the
full packet number MUST be included; it is not to be truncated, as
described below.
'''

[[spec]]
level = "MUST"
quote = '''
After an acknowledgment is received for a packet number space, the
sender MUST use a packet number size able to represent more than
twice as large a range as the difference between the largest
acknowledged packet number and the packet number being sent.
'''

[[spec]]
level = "SHOULD"
quote = '''
An endpoint SHOULD
use a large enough packet number encoding to allow the packet number
to be recovered even if the packet arrives after packets that are
sent afterwards.
'''