What does BC stand for (besides British Columbia) elsewhere
That is a great question. I looked it up, and before Before Christ,
ante Christum was popular. So then you'd have AC and AD and they'd both be in Latin and everything was in the
lingua franca of Europe. However,
ante Christum became popular in the early 1600s, whereas
Anno Domini dates to the late 700. Perhaps that much longer history, combined with talking more about the recent past as opposed to the very distant past, contributed to why the Latin
Anno Domini persists to this day in the English-speaking world, whereas
ante Christum was replaced by the vernacular.
On the one hand I like GC as it makes it clear which calendar is being referred to. But BGC - before Gregorian calendar - is less clear without established context. Before the Gregorian calendar was often the Julian calendar, and in some contexts, such as early-1900s Russian history or in parts of the Reformation, it is used to clarify that distinction.
My best prediction is that the default date system will be a configurable option. I personally find it a bit silly to replace the AD/BC abbreviations with CE/BCE, with the same dates, as that still implies that the distinguishing event of the "Common Era" was the birth of Jesus. The only reason I can think of to choose that as the distinguishing point is the religious implications, so CE/BCE puts only the thinnest of veneer over the religious dating system. But ultimately,
some reference point must be chosen, it's very difficult to choose a demarcation point that doesn't have religious or political implications, and there are benefits to having a common point of reference. If we all used the AUC system with our respective founding dates of cities of residence as the demarcation point, we'd have a mathematical conversion headache every time we talked about history. Which is probably what happened frequently in ancient times, when AUC was the system of choice, or else the point at which the current monarch or dynasty or consul began. One thing I really appreciate about English translations of Roman historians' works is that the dating system is generally converted into what's common today.
But just as Civ3 allows you to change the date system in a mod, we can make it configurable. Playing a Visigothic scenario? Use the
Era of Caesar. Roman? Use AUC. Epic game? Your choice of BC/AD or BCE/CE, or create a mod with your own preference. What we probably won't do is make the demarcation point dynamic. AUC from the time your first city is founded, then AD after Christianity is founded, or the Islamic calendar once Islam is founded? Aside from religions being a Civ4 rather than Civ3 feature, that would likely add more complexity than enjoyment due to added immersion.
Has anyone mentioned yet in this thread that naming things is a hard problem?
I've never Googled it) of Latin, and - What does BC stand for (besides British Columbia) elsewhere 
*) addressing Y2K issues, at the then second largest US bank - that "Pivotal Year 0" is the standard for finance, air traffic controllers, the military ... Even large Asian countries long ago adopted the "Year Zero Thing."
