Add checksum for EIK property in Wikidata

[mariana-angelova]

EIK property proposal URL -> https://www.wikidata.org/wiki/Wikidata:Property_proposal/EIK (search for "checksum algorithm"). In brief:

• After the prop is created:
• We want to add a SPARQL Complex constraint to find EIK with wrong checksum.
• A checksum algorithm is at https://gist.github.com/vstoykov/4344506 and includes two parts: for EIK-9 and for EIK-13.
• An example of adding checksum checking can be seen at https://www.wikidata.org/wiki/Property_talk:P212 Complex constraint "Invalid ISBN-13"
  • and results at https://www.wikidata.org/wiki/Wikidata:Database_reports/Complex_constraint_violations/P212.

@VladimirAlexiev can provide help or additional information.