The default representation of dates is a compact string such as <<.value 20211002153802059>>. The associated template is `[UTC]YYYY0MM0DD0hh0mm0ss0XXX`. For example, the <<.field created>> and <<.field modified>> fields are stored like this.
The display format for this string can be controlled with a template. For example, transcluding the <<.field modified>> field automatically applies a template to display the date as <<.value "Sat Oct 02 2021 17:40:50 GMT+0200 (Central European Summer Time)">>. A few widgets and filter operators allow you to manually specify a template, for example the ViewWidget:
|`TIMESTAMP` |<<.from-version "5.2.4">> Number of milliseconds since the [[ECMAScript epoch|https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date#the_ecmascript_epoch_and_timestamps]], 1 January 1970. |
The `{era:BCE||CE}` notation can specify different strings for years that are negative, zero or positive. For example `{era:BC|Z|AD}` would display <<.value BC>> for negative years, <<.value AD>> for positive years, and <<.value Z>> for year zero.
You can calculate the difference between two dates by doing the following:
# Convert both dates to timestamps
# Subtract the later date from the earlier one -- if you don't know which one is earlier use the <<.olink "abs">> operator to get an absolute value after subtraction
# Divide the resulting number by the number of milliseconds in your chosen interval
Here is an example of calculating the number of days that passed between creation and last modification of current tiddler:
