From the schema
A globally unique identifier for this activity. This should be in the form of the IATI Organisation Identifier (for the reporting organisation) concatenated to that organisation's activity identifier. (NB. Two or more reporting organisations may publish information on the same activity. To cross-reference these reports the other-identifier element should be used.)
Compliance1 compliance test(s) for /iati-identifier
- iati-identifier starts with the reporting-organisation ref
- iati-identifier has no leading or trailing whitespace
This is a globally unique identifier for this activity.
This is a concatenation of the unique organisation identifier (for the reporting organisation) and the organisation's activity identifier.
The example below is for an Oxfam (identified by GB-CHC-202918) activity, with their internal unique ref. of HECA91
This example is illustrated from the World Bank (44000):