I just enable Nepomuk indexing and in Dolphin entered timeline/calendar/ and the only files displayed are for 2013, the current year. Is there a way to have timeline display previous years? A range of months, days or years? Test shows earlier year files have been indexed so they should be available for timeline to display.

regards,

Know what? --- I'd not noticed that...
"timeline:/calendar/" does indeed only display the current year.
Manually entering YYYY-MM, for example, "timeline:/calendar/2012-12/" will display Dec 2012. I've not discovered a way to display the whole of 2012 --- "timeline:/calendar/2012/", or "timeline:/2012/" doesn't work... I guess you'd already found that.

I wonder if this behaviour is by design, or a bug. I'll probably file a bug report tomorrow, see what response it brings.

Edit: Just had a quick look on bugs.kde.org - seems it's by design, there's already a few requests to enhance the timeline capability:
https://bugs.kde.org/show_bug.cgi?id=304854
https://bugs.kde.org/show_bug.cgi?id=304895
https://bugs.kde.org/show_bug.cgi?id=304893
https://bugs.kde.org/show_bug.cgi?id=327596