target = "https://www.rfc-editor.org/rfc/rfc9000#section-13.2.5"

# 13.2.5.  Measuring and Reporting Host Delay
#
# An endpoint measures the delays intentionally introduced between the
# time the packet with the largest packet number is received and the
# time an acknowledgment is sent.  The endpoint encodes this
# acknowledgment delay in the ACK Delay field of an ACK frame; see
# Section 19.3.  This allows the receiver of the ACK frame to adjust
# for any intentional delays, which is important for getting a better
# estimate of the path RTT when acknowledgments are delayed.
# 
# A packet might be held in the OS kernel or elsewhere on the host
# before being processed.  An endpoint MUST NOT include delays that it
# does not control when populating the ACK Delay field in an ACK frame.
# However, endpoints SHOULD include buffering delays caused by
# unavailability of decryption keys, since these delays can be large
# and are likely to be non-repeating.
# 
# When the measured acknowledgment delay is larger than its
# max_ack_delay, an endpoint SHOULD report the measured delay.  This
# information is especially useful during the handshake when delays
# might be large; see Section 13.2.1.

[[spec]]
level = "MUST"
quote = '''
An endpoint MUST NOT include delays that it
does not control when populating the ACK Delay field in an ACK frame.
'''

[[spec]]
level = "SHOULD"
quote = '''
However, endpoints SHOULD include buffering delays caused by
unavailability of decryption keys, since these delays can be large
and are likely to be non-repeating.
'''

[[spec]]
level = "SHOULD"
quote = '''
When the measured acknowledgment delay is larger than its
max_ack_delay, an endpoint SHOULD report the measured delay.
'''