| http‑date | → | rfc‑1123‑date | rfc‑850‑date | asc‑time‑date |
| rfc‑1123‑date | → | wkday , sp date1 sp time sp GMT |
| rfc‑850‑date | → | weekday , sp date2 sp time sp GMT |
| asc‑time‑date | → | wkday sp date3 sp time sp year |
| date1 | → | day sp month sp year |
| date2 | → | day - month - year2 |
| date3 | → | month sp (day | day1) |
| year | → | digit digit digit digit |
| year2 | → | digit digit |
| day | → | digit digit |
| day1 | → | sp digit |
| wkday | → | Mon | Tue | Wed | Thu | Fri | Sat | Sun |
| weekday | → | Monday | Tuesday | Wednesday | Thursday | Friday | Saturday | Sunday |
| month | → | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
| time | → | hour : min : sec |
| hour | → | digit digit |
| min | → | digit digit |
| sec | → | digit digit |
| delta‑seconds | → | digit+ |
| sp | → | |
| digit | → | [0-9] |