target = "https://www.rfc-editor.org/rfc/rfc9000#section-19.19"

# 19.19.  CONNECTION_CLOSE Frames
#
# An endpoint sends a CONNECTION_CLOSE frame (type=0x1c or 0x1d) to
# notify its peer that the connection is being closed.  The
# CONNECTION_CLOSE frame with a type of 0x1c is used to signal errors
# at only the QUIC layer, or the absence of errors (with the NO_ERROR
# code).  The CONNECTION_CLOSE frame with a type of 0x1d is used to
# signal an error with the application that uses QUIC.
# 
# If there are open streams that have not been explicitly closed, they
# are implicitly closed when the connection is closed.
# 
# CONNECTION_CLOSE frames are formatted as shown in Figure 43.
# 
# CONNECTION_CLOSE Frame {
#   Type (i) = 0x1c..0x1d,
#   Error Code (i),
#   [Frame Type (i)],
#   Reason Phrase Length (i),
#   Reason Phrase (..),
# }
# 
#                Figure 43: CONNECTION_CLOSE Frame Format
# 
# CONNECTION_CLOSE frames contain the following fields:
# 
# Error Code:  A variable-length integer that indicates the reason for
#    closing this connection.  A CONNECTION_CLOSE frame of type 0x1c
#    uses codes from the space defined in Section 20.1.  A
#    CONNECTION_CLOSE frame of type 0x1d uses codes defined by the
#    application protocol; see Section 20.2.
# 
# Frame Type:  A variable-length integer encoding the type of frame
#    that triggered the error.  A value of 0 (equivalent to the mention
#    of the PADDING frame) is used when the frame type is unknown.  The
#    application-specific variant of CONNECTION_CLOSE (type 0x1d) does
#    not include this field.
# 
# Reason Phrase Length:  A variable-length integer specifying the
#    length of the reason phrase in bytes.  Because a CONNECTION_CLOSE
#    frame cannot be split between packets, any limits on packet size
#    will also limit the space available for a reason phrase.
# 
# Reason Phrase:  Additional diagnostic information for the closure.
#    This can be zero length if the sender chooses not to give details
#    beyond the Error Code value.  This SHOULD be a UTF-8 encoded
#    string [RFC3629], though the frame does not carry information,
#    such as language tags, that would aid comprehension by any entity
#    other than the one that created the text.
# 
# The application-specific variant of CONNECTION_CLOSE (type 0x1d) can
# only be sent using 0-RTT or 1-RTT packets; see Section 12.5.  When an
# application wishes to abandon a connection during the handshake, an
# endpoint can send a CONNECTION_CLOSE frame (type 0x1c) with an error
# code of APPLICATION_ERROR in an Initial or Handshake packet.

[[spec]]
level = "SHOULD"
quote = '''
This SHOULD be a UTF-8 encoded
string [RFC3629], though the frame does not carry information,
such as language tags, that would aid comprehension by any entity
other than the one that created the text.
'''