Category:Eras is for the organization of time by era, rather than by specific units of time measurement. Organization is maintained on this page by splitting eras where the epoch — that is, the first event of the era — is known, from those where the epoch is not known. If the epoch is not known, then the page is organized alphabetically, as with Sumaran Era. However, if the epoch is known, or at least relatively known, then the pages are organized by a numerical system, which attempts to place the epochs relative to each other. This is accomplished by giving the relevant pages a three-digit sort key attached to the category tag, beginning with the numbers 1, 2, 3, 4, or 5.

• 1 is for the very earliest events in DWU history, the so-called distant past.
• 2 is for the Dark Times, events that came immediately after events like the Big Bang, but well before most other events.
• 3 is for things that happened after the first stirrings of Rassilon.
• 4 is for human history. This is the subhead that really uses the 3-digit sort keys, because so many eras pertain to human history. Renaissance is coded as 450, the Edwardian era as 477. As new pages are added, they should attempt to slot in with their own sort codes that make chronological "sense" in this scale.
• 5 is for things that happened in the year ranges indicated on Far future — basically from about the year 10,000 to the end of time.

Remember, this is a page of inexact time-keeping. It's possible for eras to overlap, as the Renaissance does with the Elizabethan era, or the Dark Times do with the Distant past. However, organization here is by the first event of the era, not the entirety of the era.