You may have reached this page because:
- You were editing a service listview in OP5 Monitor,
- Added a rule and selected 'last_state_change' from the first drop-down (where the default value is 'this'),
Clicked into the page it created underneath, which has a red banner that reads:
Error: Don't know how to translate "" into a date, please click here for information on supported data formats.
- Then you clicked on the word 'here'. You are one click away from the answer you seek.
Ninja uses the PHP call 'DateTime::createFromFormat' to determine the acceptable values. PHP's page for this module provides the full list of parameters, along with an impressive set of examples.