Modify Inventory Instance to MARC Bib record mapping rules file

Purpose:
Libraries depending on their profiles might have a different needs for inventory instance to MARC Bib mappings. For example, a music library will have a different needs from the library that has mainly cartographic collection. Also, some libraries may choose to have more detailed MARC Bib record than others. This user story is limited to the backend functionality that would allow to modify the standard mapping rules file. The calls made by API might later be used by command line

Scenario:

• Given: A standard mapping rules file
• When: Working on specific library needs
• Then: a mapping for a specific filed can be added, removed or updated

Acceptance criteria:

• MARC bib record is generated according to the modified rules
• Mapping rules file is tenant specific
• Unit tests are written
• API tests are written