The calendar of Perqend is the only thing that the four nations can agree upon, and even then not very well.
Here’s an example of their dating Scheme
Taken from the Scout Report for Landing Location #1
The first number is the Day, second is the Month, third is the Year, and last is the Century. There are 30 days each month, 20 months a year, and obviously 100 years a century.
For an equivalent for today’s date, 3-18-16 as of writing this:
Each nation calls these numbers different things, but here’s what Koilth has them as.