Hi Kenneth,
Here is what I did:
1. Create the Template Variable where the event date will be entered
Create a template variable called eg. eventDate
Input type: Date
Widget: Unixtime
Assign this TV to the template you will use for your event items.
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2. Create the Ditto call
This is the Ditto call that I use:
[[Ditto? &parents=`2` &display=`10` &summarize=`100` &removeChunk=`Comments` &tpl=`ditto_blog` &paginate=`1` &extenders=`summary,dateFilter` &paginateAlwaysShowLinks=`0` &tagData=`documentTags` &sortBy=`eventDate` &dateSource=`eventDate` &id=`archive` &dateFormat=`%d %B %Y`]]
Note: &sortBy=`eventDate` &dateSource=`eventDate`
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3. Create your event items
And assign a date in the eventDate TV. Ditto will be able to sort your events past/present/future.
See also this tutorial from Mark Kaplan (Ditto’s creator):
http://ditto.modxcms.com/tutorials/sort-by-a-date-tv.html
Hope that helps