Relation pm#when_relation (?,?)
  supertype:  wh-/how_relation  this type permits to categorize relations according to the usual who/what/why/where/when/how questions ; this is a traditional but very subjective and ineffective way of categorizing relations 
  subtype:  relation_to_time (*,time_measure)
     subtype:  relation_from_situation_to_time (situation,time_measure)
        subtype:  time (situation,time_measure)
           subtype:  date (situation -> time_measure)
        subtype:  duration (situation -> time_measure)
        subtype:  from_time (situation -> time_measure)
           subtype:  departure_time__departuretime (process -> time_measure)
        subtype:  until_time__untiltime__to_time (situation -> time_measure)
           subtype:  arrival_time__arrivaltime (process -> time_measure)
        subtype:  before_time (situation,time_measure)
     subtype:  relation_from_time_to_time (time_measure,time_measure)
        subtype:  near_time (time_measure,time_measure)
        subtype:  before (time_measure,time_measure)
        subtype:  after (time_measure,time_measure)
     subtype:  relation_from_physical_entity_to_time (physical_entity -> time_measure)
        subtype:  check-in__checkin (physical_entity -> time_measure)
        subtype:  check-out__checkout (physical_entity -> time_measure)
     subtype:  creation_date (*,time_measure)
        subtype:  first_release__firstrelease (*,time_measure)
  subtype:  relation_from_situation_to_situation (situation,situation)
     subtype:  later_situation__latersituation (situation,situation)
        subtype:  next_situation (situation -> situation)
           subtype:  successor (situation -> situation)
        subtype:  ending_situation__termination (situation -> situation)
        subtype:  postcondition (process,situation)
        subtype:  consequence (situation,situation)  see also rst#effect
     subtype:  before_situation (situation,situation)  in WebKB, do not use these relations, use their inverses
        subtype:  previous_situation (situation -> situation)
        subtype:  beginning_situation__beginningsituation (situation -> situation)
        subtype:  precondition (process,situation)
        subtype:  cause (situation,situation)  see also rst#cause
           subtype:  causes (process,process)  the process in the 1st argument brings about the process in the 2nd argument
  subtype:  temporal_relation (?,?)
     subtype:  relation_from_time_to_situation (time_measure,situation)
     subtype:  relation_to_time (*,time_measure)
     subtype:  temporal_relation (?,?)
        subtype:  temporal_relation_from_time_point (time_point,nonnegative_integer)
           subtype:  second-of (time_point,nonnegative_integer)
           subtype:  minute-of (time_point,nonnegative_integer)
           subtype:  hour-of (time_point,nonnegative_integer)
           subtype:  day-of__dayof (time_point,nonnegative_integer)
           subtype:  month-of__monthof (time_point,nonnegative_integer)
           subtype:  year-of (time_point,nonnegative_integer)
        subtype:  temporal_relation_from_time_interval (time_interval,temporal_region)
           subtype:  begins-at-time-point (time_interval,time_point)
           subtype:  ends-at-time-point (time_interval,time_point)
           subtype:  has-duration__hasduration (time_interval,time_duration)
        subtype:  has-time-interval (temporal_thing,time_interval)
        subtype:  in-timezone (time_position,integer)
     subtype:  time (physical,time_position)  means that temporal lifespan of the 1st argument includes the time_position in the 2nd argument, i.e. the 1st argument existed or occurred at that time_position; sumo#time does for instances of physical what sumo#holds_during does for instances of sumo#formula; sumo#located and sumo#time are the basic spatial and temporal predicates, respectively
     subtype:  temporal_part (?,?)
     subtype:  begin_fn__beginfn (?,?)
     subtype:  end_fn__endfn (?,?)
     subtype:  starts (?,?)
     subtype:  finishes (?,?)
     subtype:  before (?,?)
     subtype:  before_or_equal (?,?)
     subtype:  temporally_between (?,?)
     subtype:  temporally_between_or_equal (?,?)
     subtype:  overlaps_temporally (?,?)
     subtype:  meets_temporally__meetstemporally (?,?)
     subtype:  earlier (?,?)
     subtype:  cooccur (?,?)
     subtype:  time_interval_fn (?,?)
     subtype:  recurrent_time_interval_fn (?,?)
     subtype:  when_fn (physical -> time_interval)  maps an object or process ?p to the exact time_interval during which it exists (for every time_point ?t outside of the time_interval, (time ?p ?t) does not hold
     subtype:  past_fn (?,?)
     subtype:  immediate_past_fn (?,?)
     subtype:  future_fn (?,?)
     subtype:  immediate_future_fn (?,?)
     subtype:  year_fn (?,?)
     subtype:  month_fn__monthfn (?,?)
     subtype:  day_fn__dayfn (?,?)
     subtype:  hour_fn (?,?)
     subtype:  minute_fn (?,?)
     subtype:  second_fn (?,?)
     subtype:  temporal_composition_fn (?,?)
     subtype:  relative_time_fn (?,?)
     subtype:  holds_during__holdsduring (time_position,formula)  means that the proposition denoted by is true at (every temporal_part of) the time_position