https://userapps.support.sap.com/sap/support/knowledge/en/2420350
2420350 - SLD: Bases Intervals Generation | SAP Knowledge Base Article
This KBA will help to clarify how the report RPC_PAYES_CRETA_BASES creates the intervals of the bases file that must be sent to spanish Social Insurance.
sap knowledgesldbasesintervalsgeneration