TheHTTP headers reference documents the header section of request and response messages in the Hypertext Transfer Protocol (HTTP).This article explains how to create a new reference page for an HTTP header.

Step 1 – Determine the HTTP header to document

• There are many HTTP headers defined in various IETF standards.
• IANA maintains aregistry of HTTP header fields and Wikipedia lists theknown header fields, but not all are relevant to web developers or are part of an official standard.
• If there are anyred links on the currentHTTP headers reference overview page, these headers are a good choice to document.
• If in doubt,ask the MDN Web Docs team whether or not it makes sense to write about the header you have chosen.

Step 2 – Check the existing HTTP header pages

• Existing HTTP headers are documentedin the HTTP reference.
• There are different header categories:Request header,Response header, andRepresentation header.
• Find the category of the header you are about to document (note that some headers can be both request and response headers, depending on the context).
• Go to an existing header reference page that has the same category.

Step 3 – Create the HTTP header page

• All header pages live under this tree:files/en-us/web/http/reference/headers
• To create a new page, see the instructions in ourhow to create a page guide.

Step 4 – Write the content

• Either start from ourtemplate HTTP header page or use a copied structure from one of the existing HTTP header documents that you found in step 2. It's your choice.
• Write about the new HTTP header.
• Make sure you have these sections:
  • Introductory text where the first sentence mentions the header name (bold) and summarizes its purpose.
  • Information box containing at least the header type and if the header is aForbidden request header.
  • A syntax box containing all possible directives/parameters/values of the HTTP header.
  • A section that explains these directives/values.
  • An example section that contains a practical use case for this header or shows where and how it occurs usually.
  • A specification section listing relevant RFC standard documents.
  • A "See also" section listing relevant resources.

Step 5 – Add browser compatibility information

• If you have looked at other HTTP header pages, you will see that there is a{{Compat}} macro that will fill in a browser table for you.
• The compatibility table page is generated from structured data. If you'd like to contribute to the data, please check out the instructions athttps://github.com/mdn/browser-compat-data/blob/main/README.md and send us a pull request.

Step 6 – Update the HTTP headers list

Make sure your header is listed in an appropriate category on theHTTP headers reference overview page.

Step 7 – Get the content reviewed

After you've created the header page, submit it as a pull request. A member of our review team will be assigned automatically to review your page.