(re-opening idea from: “Add xs:duration attribute to certain dates” with clarifications)
Suggestion to allow periods of time as well as events. Could use additional xs:duration for elements such as transaction/transaction date where it is not necessary to have the date as an event in time (as opposed to transaction/value/@value-date or activity-date/@iso-date which must be events , eg for the former the date is for currency conversion, the latter it is not known a priori eg. the end-actual date)
Clarifications: without xs:duration how would you reliably determine the length of time that eg. a transaction spans - it could be a monthly aggregation, quarterly, yearly etc. – current IATI documentation suggests one has to read free-text: http://iatistandard.org/201/activity-standard/iati-activities/iati-activity/transaction/transaction-date/ "The narrative content may contain text (e.g. 2011Q1) for accurately recording less specific dates such as month, quarter, or year." I imagine this would affect any visualisation trying to create a “per month” value from IATI data.