It was just an idea for string in not rendered date (when cursor is in item with date) I saw yesterday different topic where someone was asking about specifying duration - maybe it could be merged in that way:
this will be synced and should occupy 2 hours in calendar:
!(2017-05-13 10:00)[duration:2h sync:yes]
or 1h 30m
!(2017-05-13 10:00)[duration:1h30m sync:yes]
this should not be synced but has duration (duration should be shown in some way when date is rendered for user, maybe if now is 9:00 then it should be stated like: “in an hour - for 2 hours”):
!(2017-05-13 10:00)[duration:2h sync:no]
and this is simple date without duration which should also not be synced
!(2017-05-13 10:00)[sync:no]
or maybe by default, when syncing is not checked in date picker, this should be simple as:
!(2017-05-13 10:00)
I think that with syntax like that it could be easily extended to contain information about recurring task etc.
Just an idea