The P4 file is an XML file format with Session and MRR Events sections and an XSD that defines the file format requirements. The Session contains the File Name, which acts as the key to identify the unique set of records contained within the file. The Session section also contains metadata about when the file was created, for which MRR project, and for what purpose. The MRR Events section contains one record for each PIT tag Mark, Recapture or Recovery contained within the file.

 

There have been three versions of the P4 file used for production data submission. The version number can be found in the File Version element in the Session section of the file, except for version 1, where this element does not exist.