Info dir

OpenCitations Meta assigns unique identifiers (OMIDs) to each entity. The numbering is tracked on the filesystem in an info_dir directory, where counter files store the last assigned number for each entity type and supplier prefix.

When processing data, the system reads the current counter value, increments it, and uses that number for the new entity URI. For example, if the counter for br (bibliographic resource) with prefix 0610 is at 1000, the next entity will be https://w3id.org/oc/meta/br/06101001.

The info dir also tracks provenance snapshot counters. Each time an entity is modified, a new provenance snapshot is created with an incremental number.

Structure

Counter files are stored in base_output_dir/info_dir/<supplier_prefix>/ with names following this pattern:

• Entity counters: info_file_{short_name}.txt → last assigned number

• Provenance counters: prov_file_{short_name}.txt → provenance snapshot counters

Where short_name is one of: br, ra, ar, re, id.

When to use these scripts

• After importing existing data: if you load RDF files from another source, you need to generate the info dir so that new entities don’t overlap with existing ones

• After a system failure: if counter files are lost, you can rebuild them from the RDF files

• To verify consistency: check that counter files match the actual data in the RDF files