| Attribute | Source | Description |
|---|---|---|
| Allow | rfc1945 | Gives allowed http methods |
| Alternates | rfc2068 | List alternate representations |
| Bulletin-Date | Lotus | Date, e.g. 1997-03-24 15:57 |
| Bulletin-Text | Lotus | Document description |
| Cache-Control | rfc2068 | Directives to cacheing mechanisms |
| Content-Base | rfc2068 | Specify base URL for entity |
| Content-Encoding | rfc1945 | Gives compression scheme |
| Content-language | rfc1945 | Natural Language of document |
| Content-Length | rfc1945 | Size of body in bytes |
| Content-Location | rfc2068 | Resource location for entity |
| Content-MD5 | rfc2068 | MD5 digest of entity body |
| Content-Range | rfc2068 | Range of partial response |
| Content-Type | rfc1945 | Media type |
| Content-type | rfc1945 | |
| Content-Version | rfc2068 | Version tag of evolving entity |
| Date | rfc1945 | Date message originated (HTTP format) |
| Derived-From | rfc2068 | Version tag of previous version |
| ETag | rfc2068 | Entity tag for resource identification |
| Expires | rfc1945 | Expiry date of document (HTTP date format) |
| Ext-cache | Netscape | Alternate cache path |
| Instance-Delegate | SHOE | Pointer to Ontology Key |
| Instance-Key | SHOE | Ontology Key |
| Last-Modified | rfc1945 | Date resource was last changed |
| Link | rfc1945 | Relationship to other resources |
| Location | rfc1945 | URL of resource |
| MIME-Version | rfc1945 | May indicate MIME-compliance. Ignore. |
| PICS-Label | PICS | Document content labelling |
| Pragma | rfc1945 | no-cache prevents cacheing |
| Public | rfc2068 | List of supported methods by server |
| Range | rfc2068 | Specify subrange (bytes) |
| Refresh | Netscape | Delay till browser reloads (optional URL) |
| Server | rfc1945 | Gives information about server |
| Title | rfc1945 | Title of entity (obsoleted in rfc2068) |
| Transfer-Encoding | rfc2068 | Specify transfer (cf. entity) encoding |
| URI | rfc1945 | URIs by which resource is located. (obsoleted in rfc2068) |
| Vary | rfc2068 | Specify that request was selected from alternates (e.g. different languages) |
| Via | rfc2068 | Generated by gateways |
| Warning | rfc2068 | Warning about cache problems, etc. |
| Window-target | Netscape | Specify target window of current document |