target = "https://www.rfc-editor.org/rfc/rfc9000#section-19.21"

# 19.21.  Extension Frames
#
# QUIC frames do not use a self-describing encoding.  An endpoint
# therefore needs to understand the syntax of all frames before it can
# successfully process a packet.  This allows for efficient encoding of
# frames, but it means that an endpoint cannot send a frame of a type
# that is unknown to its peer.
# 
# An extension to QUIC that wishes to use a new type of frame MUST
# first ensure that a peer is able to understand the frame.  An
# endpoint can use a transport parameter to signal its willingness to
# receive extension frame types.  One transport parameter can indicate
# support for one or more extension frame types.
# 
# Extensions that modify or replace core protocol functionality
# (including frame types) will be difficult to combine with other
# extensions that modify or replace the same functionality unless the
# behavior of the combination is explicitly defined.  Such extensions
# SHOULD define their interaction with previously defined extensions
# modifying the same protocol components.
# 
# Extension frames MUST be congestion controlled and MUST cause an ACK
# frame to be sent.  The exception is extension frames that replace or
# supplement the ACK frame.  Extension frames are not included in flow
# control unless specified in the extension.
# 
# An IANA registry is used to manage the assignment of frame types; see
# Section 22.4.

[[spec]]
level = "MUST"
quote = '''
An extension to QUIC that wishes to use a new type of frame MUST
first ensure that a peer is able to understand the frame.
'''

[[spec]]
level = "SHOULD"
quote = '''
Such extensions
SHOULD define their interaction with previously defined extensions
modifying the same protocol components.
'''

[[spec]]
level = "MUST"
quote = '''
Extension frames MUST be congestion controlled and MUST cause an ACK
frame to be sent.
'''

[[spec]]
level = "MUST"
quote = '''
Extension frames MUST be congestion controlled and MUST cause an ACK
frame to be sent.
'''