usually, but not always, within infobox or similar templates, or tables.
See the microformats project for further details.
This template has no provision to deal with a date in a non-Gregorian calendar. Also, ISO 8601 requires mutual agreement among those exchanging information before using years outside the range 1583-9999 CE. Therefore, use of this template for non-Gregorian dates or dates outside that range constitutes a false claim of conformance to the ISO 8601 standard.
Any editor encountering such usage should change the date to plain text with no template; or if not confident in doing so, raise the matter on this template's talk page.