target = "https://www.rfc-editor.org/rfc/rfc8312#section-4.4"

# 4.4.  Convex Region
#
# When receiving an ACK in congestion avoidance, if CUBIC is not in the
# TCP-friendly region and cwnd is larger than or equal to W_max, then
# CUBIC is in the convex region.  The convex region indicates that the
# network conditions might have been perturbed since the last
# congestion event, possibly implying more available bandwidth after
# some flow departures.  Since the Internet is highly asynchronous,
# some amount of perturbation is always possible without causing a
# major change in available bandwidth.  In this region, CUBIC is being
# very careful by very slowly increasing its window size.  The convex
# profile ensures that the window increases very slowly at the
# beginning and gradually increases its increase rate.  We also call
# this region the "maximum probing phase" since CUBIC is searching for
# a new W_max.  In this region, cwnd MUST be incremented by
# (W_cubic(t+RTT) - cwnd)/cwnd for each received ACK, where
# W_cubic(t+RTT) is calculated using Eq. 1.

[[spec]]
level = "MUST"
quote = '''
In this region, cwnd MUST be incremented by
(W_cubic(t+RTT) - cwnd)/cwnd for each received ACK, where
W_cubic(t+RTT) is calculated using Eq.
'''