The first XBRL International Inc (XII) packaging specification, developed in 2015, was aimed solely at providing a standard mechanism for packaging XBRL taxonomies, not reports, in ZIP archives (a compressed, portable, single file containing a directory and file hierarchy).

In 2018 XII produced a Working Group Note (WGN) which recognises the Specification might also be applicable to the packaging of reports and sets out the preferred approach for including XBRL and/or Inline XBRL reports within taxonomy packages. This mainly comprises the establishment of conventions for the location and naming of reports within the package; no changes to the Taxonomy Packages specification itself were proposed.

Adoption of the WGN by ESMA along with other demands for packaging reports has prompted XII to re-visit this topic and examine it in more detail. An initial Public Working Draft (PWD) for Report Packages was published in December 2020 but the thinking has been continually evolving since then. This has led to the identification of three distinct use-cases: multi-report submission; multi-report publication; and portable XBRL reports. In effect the WGN, and therefore the ESEF by implication, belong to the first category, multi-report submission, though there is a feeling that ESEF reports ought ultimately to be regarded as self-contained portable XBRL reports.

Implementation-wise, current thinking refers to “white box” and “black box” packaging solutions:

  • White Box = .zip extension and arbitrary content allowed (this is the XII WGN approach)
  • Black Box = specialised extension and tightly-defined content, never intended to be unzipped 

XII have made the pragmatic decision to pursue a white box packaging specification in the first instance, with a black box portable report format in due course. This will likely be an evolution of the WGN to build on the taxonomy package specification and formalise file and directory location and naming, as well as providing appropriate package meta-data to help consumers understand and process the contents correctly. The current feeling is that a Recommendation can be agreed upon and published before the end of 2021.

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