Thanks for your reply James,
The feature list would depend on whether a majority of users actually want a full fledged calendar app in tandem with GTDN or whether they just want to be able to visualize their data in a calendar format. Sticking to a GTD interpretation the gtdn calendar should be reserved for the hard lines. Meaning appointments and projects with deadlines or start times that you want to show up in the Cal. to my knowledge, we can't yet record a clock time specific entry in gtdn and we would need that feature to be able to push it to the calendar and be functional. That could be taken care of by a subset of calendar variables in its own box on the right panel Like:
Title: Abbreviated Identifier to appear in the calendar
Start time & Date
End Time & Date
Link back to entry in gtdn
Outbound link to some other page
Option to have d-box and drive linked files to the entry to show up in the Cal
Delay Function: meaning have the item appear at a specific time and date in the Cal
Field for additional info like Description
Reminder: Some kind of notification option.
NICE TO HAVE:
Color coded Holiday Calendars like google Cal.