Master Data 
All master data is available locally in the SAP Supplier Relationship Management (SRM) system. This data includes, for example, product master records, business partner master records, and product categories. You copy the master data from the back-end system to SAP SRM.
Note
In SAP SRM, both materials and services are stored as products. However, you can distinguish materials from services by the product type.
Product categories correspond to material groups in the SAP back-end system.
Business partner master records correspond to supplier master records in the SAP back-end system.
If the SAP SRM system communicates with an SAP back-end system, the length of the product ID has been restricted to a maximum of 18 characters. This should be the case even if the products are created locally, and not replicated from the back-end system. If you assign a product ID with more than 18 characters, a different number (with a maximum of 18 characters) has to be assigned in the back-end system.
You have applied the delivered Business Add-Ins (BAdIs) to make sure that product IDs are unique across all systems. See Customizing: and Influence External Number Assignment.
Caution
If these recommendations are not observed, you could have mismatched product or material numbers between your back-end, SAP SRM, and other systems.
For information about the replication of supplier master records, see Manage External Business Partners.
For information about the replication of material and supplier master records in the product master, see SAP Solution Manager under , choose the Configuration tab and open the document Replication of Materials from SAP Backend Systems.
For information about product categories, see Product Categories
For more information about SRM-MDM Catalog, see SAP Help Portal at http://help.sap.com .