update
Now the property is named Software Heritage identifier (SWHID)
and today the regexp was corrected to all types of SWHIDs by Kat (Thank you Kat!!)
Also the documentation link and references to both articles were added:

• documentation page: https://docs.softwareheritage.org/devel/swh-model/persistent-identifiers.html
• references:
  • Roberto Di Cosmo, Morane Gruenpeter, Stefano Zacchiroli. Identifiers for Digital Objects: the Case of Software Source Code Preservation. In Proceedings of iPRES 2018: 15th International Conference on Digital Preservation, Boston, MA, USA, September 2018, 9 pages.
    • DOI: 10.17605/OSF.IO/KDE56
    • PDF: https://www.softwareheritage.org/wp-content/uploads/2020/01/ipres-2018-swh.pdf
    • HAL-ID: hal-01865790
  • Roberto Di Cosmo, Morane Gruenpeter, Stefano Zacchiroli. Referencing Source Code Artifacts: a Separate Concern in Software Citation. In Computing in Science and Engineering, volume 22, issue 2, pages 33-43. ISSN 1521-9615, IEEE. March 2020.
    • DOI: 10.1109/MCSE.2019.2963148
    • HAL-ID: hal-02446202
    • pdf: https://www.softwareheritage.org/wp-content/uploads/2020/01/2020-CiSE-swhid-1.pdf

With the WikiDigi group in 2017/2018 we studied the case of SWHID property and created the https://www.wikidata.org/wiki/Property:P6138
the property was only allowing releases. This discussion is summarized and closed on T1298.

In T2079 the need to document the links between SWH and Wikidata became evident.

This is a larger discussion we should have on integration with WikiData.

The main questions were:

1. Should we modify the property to : SWHID release? SWHID?
2. Should we create a new (additional) property SWHID? including snp, rev, dir and cnt?
   
   When this is resolved we need to update the property documentation with the new contextual parameters and with the correct regexp.