BPMN2 — TimerEventDefinition: clarification of the expected result of the timeCycle and timeDate expressions

These attributes of the TimerEventDefinition are expressions, there is no mention of the result type. Also it would be useful to describe how this values are used (timeDate defines the next moment the time will trigger, while timeCycle defines an interval that is added to "now" to define the next moment).

Another thing that is not described is the moment when theses expressions are evaluated. Intuitively I think it is in the moment after the trigger is executed, and for the first time, the moment it is activated.

Following the BPEL mapping, the timeDate expression should return an XSD DateTime element and the timeCycle an XSD Interval (Period).

I think it is necessary to clarify this in the execution semantics so people understand what type of behaviour is expected from this event.

I can make the changes if necessary.

Section 10.4.5 Event Definitions
Subsection Timer Event, Table 10.20 - TimerEventDefinition model associations
> Change row: attribute timeDate
Original
If the Trigger is a Timer, then a timeDate MAY be entered. If a timeDate is not entered, then a timeCycle MUST be entered (see attribute below—if the processType
attribute of the Process is set to executable).
Proposal
If the Trigger is a Timer, then a timeDate MAY be entered. Timer attributes are mutually exclusive and if any of the other Timer attributes is set, timeDate MUST NOT
be set (see attribute below—if the processType attribute of the Process is set to executable). The return type of the attribute timeDate MUST conform to the ISO8601
format for date and time representations.
> Change row: attribute timeCycle
Original
If the Trigger is a Timer, then a timeCycle MAY be entered. Timer attributes are mutually exclusive and if any of the other Timer attributes is set, timeCycle MUST
NOT be set (see attribute below—if the processType attribute of the Process is set to executable).
The return type of the attribute timeDate MUST conform to ISO-8601 interval format.
Proposal
If the Trigger is a Timer, then a timeCycle MAY be entered. Timer attributes are mutually exclusive and if any of the other Timer attributes is set, timeCycle MUST
NOT be set (see attribute below—if the processType attribute of the Process is set to executable). The return type of the attribute timeCycle MUST conform to the
ISO-8601 format for recurring time interval representations.
> Append row: attribute timeDuration
Original
N/A
Proposal
Attribute Name
timeDuration: Expression [0..1]
Description/Usage
If the Trigger is a Timer, then a timeDuration MAY be entered to specify a relative point in time. Timer attributes are mutually exclusive and if any of the other Timer
attributes is set, timeDuration MUST NOT be set (see attribute below—if the processType attribute of the Process is set to executable). The return type of the
attribute timeDuration MUST conform to the ISO-8601 format for time interval representations.
Disposition: Resolved