# Calendars and dates ### Why the codex has calendars Some facts are only true for a while. A captain holds a rank until she's promoted; a city stands until it falls; a character is twelve in one book and forty in the next. To say *when* a fact applies, the codex needs a way to write dates—and your world may not count years the way ours does. So each universe has at least one calendar, and a fact can say "from here, to there" on it. If your books are set in the ordinary world, you can leave all of this alone. Every universe starts with a Gregorian calendar, and that's the one you'll be offered. ### Where it lives In the codex, click **Setup** at the top right. The rail that opens has a **Calendar system** card. The default calendar is already there, named *Gregorian*; rename it if your story calls it something else, and there's a table beneath, *How other worlds would write theirs*, showing how a Star Wars, Star Trek, Tolkien, Dune or Westeros calendar would be set up, in case you'd like to borrow one. ![Screenshot: the Calendar system card](https://assets.authortools.net/help/screenshot-placeholder.png) *Screenshot: the codex's Setup rail with the Calendar system card open, showing the default calendar named Gregorian and, beneath it, the table How other worlds would write theirs.* ### What a calendar needs **Calendar name**—what you see. *Gregorian*, *Stellar date*, *Imperial reckoning*. **Dates are written as**—how you'll type a date for this calendar. Five ways: - **a year, with an era if any**: 2024 · 68 CE · 44 BC · 4 ABY. The usual choice. - **month.day.year**: 11.04.8927. (Aeon 14's stellar dates are written this way.) - **day.month.year**: 04.11.8927. - **year-month-day**: 2024-05-14. - **year.day-of-year**: 8927.308. For the three with a month and a day, you can separate the parts with a dot, a slash or a dash—whichever you type is fine. **Before the zero point**—if your calendar has dates before its year one, the word that marks them: *BCE*, *BC*, *BBY*, *Before Landing*. Then "12 BCE" is understood as twelve years before. Leave it empty for a calendar that only counts forward (a stardate, say). The calendar also has a short **key** (shown when there's more than one calendar). It's what facts point at behind the scenes and doesn't change once set; the name is yours to change whenever you like. ### Writing a date Wherever the codex asks for a date—a fact's *from* and *to*, when an entry exists—type it the way the calendar says. The codex keeps exactly what you typed and shows it back the same way; underneath, it works out an order so it knows that 68 CE comes before 70 CE and 2 BCE before 1 CE. A bare year is always accepted, whatever the calendar's style, so "8927" works on a month.day.year calendar when you don't know the day. If something can't be read, the box tells you and shows the style the calendar expects. (And yes: historians skipped year zero, and so does the codex—1 BCE is followed by 1 CE.) ### A second calendar Science fiction and fantasy often need two: the world's own reckoning and, thanks to time travel or prequels, the one the readers know. Click **Add a second calendar** in the Calendar system card, give it a name and a style, and it joins the first. Every fact's *when* then says which calendar it's on, and an entry can exist on more than one—a character might have a stellar-date birth and a Gregorian one. One calendar is marked *primary*: it's the one offered first. **Make primary** changes which. ### Where dates show up - On facts: *Add book, series, or date-specific information* lets a fact run from one date to another on a calendar. - On entries: each entry can say when it exists on each calendar, or *Applies to all dates*. An entry that doesn't exist yet at the moment you're writing in won't show up when the codex is framed to that moment. - In **Working in**: for each calendar in use, choose *Any time*, or *At…* a date, or *Not on this calendar*, and the whole codex shows the world as it was then. Those three are the subject of [What's true when and where](/link/34).