"What am I doing today?"
    query(type => summary, timespan => today)

"What am I doing tomorrow?"
    query(type => summary, timespan => tomorrow)

"What am I doing on Wednesday?"
    query(type => summary, timespan => wednesday)

"What am I doing on April 9th?"
    query(type => summary, timespan => day of April 9th)

"What's going on today?"
    query(type => summary, timespan => today)

"What was I doing last week?"
    query(type => summary, timespan => last week)

"I have an appointment with Chris tomorrow."
    update(with_who => chris, type => meeting)

"There is an AzEIP meeting tomorrow which I must attend."
    update(with_who => AZEIP, type => meeting)

"I am going to the concert on july 5th"
    update(type => event, name => concert)

"I went to the concert today."
    update(type => history, name => concert)

"When is that concert?"
    query(type => detail, search_forward_for => concert)

Query types:
    summary => simple list of events, perhaps with times
    detail => excessive detail

Timespans:
    today => from midnight to midnight today
    tomorrow => from midnight to midnight tomorrow
    next week =>