7. IANA Considerations

7.1. Cache Directive Registry

The "Hypertext Transfer Protocol (HTTP) Cache Directive Registry" defines the namespace for the cache directives. It has been created and is now maintained at http://www.iana.org/assignments/http-cache-directives.

7.1.1. Procedure

A registration MUST include the following fields:

Cache Directive Name
Pointer to specification text

Values to be added to this namespace require IETF Review (see [RFC5226], Section 4.1).

7.1.2. Considerations for New Cache Control Directives

New extension directives ought to consider defining:

What it means for a directive to be specified multiple times,
When the directive does not take an argument, what it means when an argument is present,
When the directive requires an argument, what it means when it is missing,
Whether the directive is specific to requests, responses, or able to be used in either.

7.1.3. Registrations

The registry has been populated with the registrations below:

Cache Directive	Reference
max-age	Section 5.2.1.1, Section 5.2.2.8
max-stale	Section 5.2.1.2
min-fresh	Section 5.2.1.3
must-revalidate	Section 5.2.2.1
no-cache	Section 5.2.1.4, Section 5.2.2.2
no-store	Section 5.2.1.5, Section 5.2.2.3
no-transform	Section 5.2.1.6, Section 5.2.2.4
only-if-cached	Section 5.2.1.7
private	Section 5.2.2.6
proxy-revalidate	Section 5.2.2.7
public	Section 5.2.2.5
s-maxage	Section 5.2.2.9
stale-if-error	[RFC5861], Section 4
stale-while-revalidate	[RFC5861], Section 3

7.2. Warn Code Registry

The "Hypertext Transfer Protocol (HTTP) Warn Codes" registry defines the namespace for warn codes. It has been created and is now maintained at http://www.iana.org/assignments/http-warn-codes.

7.2.1. Procedure

A registration MUST include the following fields:

Warn Code (3 digits)
Short Description
Pointer to specification text

Values to be added to this namespace require IETF Review (see [RFC5226], Section 4.1).

7.2.2. Registrations

The registry has been populated with the registrations below:

Warn Code	Short Description	Reference
110	Response is Stale	Section 5.5.1
111	Revalidation Failed	Section 5.5.2
112	Disconnected Operation	Section 5.5.3
113	Heuristic Expiration	Section 5.5.4
199	Miscellaneous Warning	Section 5.5.5
214	Transformation Applied	Section 5.5.6
299	Miscellaneous Persistent Warning	Section 5.5.7

7.3. Header Field Registration

HTTP header fields are registered within the "Message Headers" registry maintained at http://www.iana.org/assignments/message-headers/.

This document defines the following HTTP header fields, so the "Permanent Message Header Field Names" registry has been updated accordingly (see [BCP90]).

Header Field Name	Protocol	Status	Reference
Age	http	standard	Section 5.1
Cache-Control	http	standard	Section 5.2
Expires	http	standard	Section 5.3
Pragma	http	standard	Section 5.4
Warning	http	standard	Section 5.5

The change controller is: "IETF ([email protected]) - Internet Engineering Task Force".

7.1. Cache Directive Registry​

7.1.1. Procedure​

7.1.2. Considerations for New Cache Control Directives​

7.1.3. Registrations​

7.2. Warn Code Registry​

7.2.1. Procedure​

7.2.2. Registrations​

7.3. Header Field Registration​