Draft: draft-ietf-quic-http

Commentary: as well as other instances of the term . RFC 7301 does indeed hyphenate ( and that 's correct , since " application - layer " is being used as a single unit to describe " protocol " ) . 
 says the registry is
Paragraph (version A):
A client MAY attempt access to a resource with an "https" URI by
resolving the host identifier to an IP address, establishing a QUIC
connection to that address on the indicated port (including
validation of the server certificate as described above), and sending
an HTTP/3 request message targeting the URI to the server over that
secured connection.  Unless some other mechanism is used to select
HTTP/3, the token "h3" is used in the Application Layer Protocol
Negotiation (ALPN; see RFC7301) extension during the TLS handshake.
Paragraph (version B):
A client MAY attempt access to a resource with an "https" URI by
resolving the host identifier to an IP address, establishing a QUIC
connection to that address on the indicated port (including
validation of the server certificate as described above), and sending
an HTTP/3 request message targeting the URI to the server over that
secured connection.  Unless some other mechanism is used to select
HTTP/3, the token "h3" is used in the Application-Layer Protocol
Negotiation (ALPN; see RFC7301) extension during the TLS handshake.
Paragraph (version A):
This document creates a new registration for the identification of
HTTP/3 in the "Application Layer Protocol Negotiation (ALPN) Protocol
IDs" registry established in RFC7301.
Paragraph (version B):
This document creates a new registration for the identification of
HTTP/3 in the "Application-Layer Protocol Negotiation (ALPN) Protocol
IDs" registry established in RFC7301.
Paragraph (version A):
The first Initial packet from a client contains the start or all of
its first cryptographic handshake message, which for TLS is the
ClientHello.  Servers might need to parse the entire ClientHello
(e.g., to access extensions such as Server Name Identification (SNI)
or Application Layer Protocol Negotiation (ALPN)) in order to decide
whether to accept the new incoming QUIC connection.  If the
ClientHello spans multiple Initial packets, such servers would need
to buffer the first received fragments, which could consume excessive
resources if the client's address has not yet been validated.  To
avoid this, servers MAY use the Retry feature (see Section 8.1 of
QUIC-TRANSPORT) to only buffer partial ClientHello messages from
clients with a validated address.
Paragraph (version B):
The first Initial packet from a client contains the start or all of
its first cryptographic handshake message, which for TLS is the
ClientHello.  Servers might need to parse the entire ClientHello
(e.g., to access extensions such as Server Name Identification (SNI)
or Application-Layer Protocol Negotiation (ALPN)) in order to decide
whether to accept the new incoming QUIC connection.  If the
ClientHello spans multiple Initial packets, such servers would need
to buffer the first received fragments, which could consume excessive
resources if the client's address has not yet been validated.  To
avoid this, servers MAY use the Retry feature (see Section 8.1 of
QUIC-TRANSPORT) to only buffer partial ClientHello messages from
clients with a validated address.
Paragraph (version A):
Application Layer Protocol Negotiation (ALPN; see ALPN) allows
clients to offer multiple application protocols during connection
establishment.  The transport parameters that a client includes
during the handshake apply to all application protocols that the
client offers.  Application protocols can recommend values for
transport parameters, such as the initial flow control limits.
However, application protocols that set constraints on values for
transport parameters could make it impossible for a client to offer
multiple application protocols if these constraints conflict.
Paragraph (version B):
Application-Layer Protocol Negotiation (ALPN; see ALPN) allows
clients to offer multiple application protocols during connection
establishment.  The transport parameters that a client includes
during the handshake apply to all application protocols that the
client offers.  Application protocols can recommend values for
transport parameters, such as the initial flow control limits.
However, application protocols that set constraints on values for
transport parameters could make it impossible for a client to offer
multiple application protocols if these constraints conflict.