Change:
-> a URI Template
but also is it "URI Template" or "URI template"? this seems inconsistent through the document

Discussion:
2. <del> Clients are configured to use UDP Proxying over HTTP via an URI </del> <ins> Clients are configured to use UDP Proxying over HTTP via a URI </ins> Template TEMPLATE with the variables "target_host" and "target_port". Examples are shown below: <del> The URI template MUST be a level 3 template or lower.  The URI template MUST be in absolute form, and MUST include non-empty scheme, </del> <ins> The URI Template MUST be a level 3 template or lower.  The URI Template MUST be in absolute form, and MUST include non-empty scheme, </ins> authority and path components.  The path component of the URI <del> template MUST start with a slash "/".  All template variables MUST be </del> <ins> Template MUST start with a slash "/".  All template variables MUST be </ins> within the path component of the URI.  The URI template MUST contain the two variables "target_host" and "target_port" and MAY contain <del> other variables.  The URI template MUST NOT contain any non-ASCII </del> <ins> other variables.  The URI Template MUST NOT contain any non-ASCII </ins> unicode characters and MUST only contain ASCII characters in the range 0x21-0x7E inclusive (note that percent-encoding is allowed). <del> The URI template MUST NOT use Reserved Expansion ("+" operator), </del> <ins> The URI Template MUST NOT use Reserved Expansion ("+" operator), </ins> Fragment Expansion ("#" operator), Label Expansion with Dot-Prefix, Path Segment Expansion with Slash-Prefix, nor Path-Style Parameter Expansion with Semicolon-Prefix.  If any of the requirements above <del> are not met by a URI template, the client MUST reject its </del> <ins> are not met by a URI Template, the client MUST reject its </ins> configuration and fail the request without sending it to the proxy. Since the original HTTP CONNECT method allowed conveying the target

A "connect-udp" request requests that the recipient proxy establish a tunnel over a single HTTP stream to the destination target identified <del> by the "target_host" and "target_port" variables of the URI template </del> <ins> by the "target_host" and "target_port" variables of the URI Template </ins> (see client-config).  If the request is successful, the proxy commits to converting received HTTP Datagrams into UDP packets and vice versa until the tunnel is closed.  Tunnels are commonly used to create an

QUIC or another protocol running over UDP. When sending its UDP proxying request, the client SHALL perform URI <del> template expansion to determine the path and query of its request. </del> <ins> Template expansion to determine the path and query of its request. </ins> target_host supports using DNS names, IPv6 literals and IPv4 <del> literals.  Note that this URI template expansion requires using pct- </del> <ins> literals.  Note that this URI Template expansion requires using pct- </ins> encoding, so for example if the target_host is "2001:db8::42", it will be encoded in the URI as "2001%3Adb8%3A%3A42".

the request SHALL include a single "Upgrade" header with value "connect-udp". <del> For example, if the client is configured with URI template </del> <ins> For example, if the client is configured with URI Template </ins> "https://proxy.example.org/.well-known/masque/ udp/{target_host}/{target_port}/" and wishes to open a UDP proxying tunnel to target 192.0.2.42:443, it could send the following request:

The ":path" and ":scheme" pseudo-header fields SHALL NOT be empty. Their values SHALL contain the scheme and path from the URI <del> template after the URI template expansion process has been </del> <ins> Template after the URI template expansion process has been </ins> completed. A UDP proxying request that does not conform to these restrictions is malformed (see H2). <del> For example, if the client is configured with URI template </del> <ins> For example, if the client is configured with URI Template </ins> "https://proxy.example.org/{target_host}/{target_port}/" and wishes to open a UDP proxying tunnel to target 192.0.2.42:443, it could send the following request: