Visualforce Developer Guide
jNote: This release is in preview. Features described here don’t become generally available until the latest general availability date that Salesforce announces for this release. Before then, and where features are noted as beta, pilot, or developer preview, we can’t guarantee general availability within any particular time frame or at all. Make your purchase decisions only on the basis of generally available products and features.
$System.OriginDateTime
A global merge field that represents the literal value of 1900-01-01
00:00:00.
Usage
Use this global variable when performing date/time offset calculations, or to assign a literal value to a date/time field.
Example
The following example calculates the number of days that have passed since January 1,
1900:
1{!NOW() - $System.OriginDateTime}