SAP BAPI : Business Application programming interfaces are standard methods to access business objects which form the core of all SAP R/3 business frameworks.
SAP PM Tables relationship Diagram (PDF)
SAP PM Tables Relationship will help you go through the complex SAP Tables landscape of SAP PM.
Here the SAP PM Tables relationship with fields join between relevant Plant Maintenance tables in SAP.
SAP Plant Maintenance?module consists of key activities to include inspection, notifications, corrective and preventive maintenance, repairs, and other measures to maintain an ideal technical system.