Extension Definition 
Extensions are data fields you can add to sourcing documents or data records. They can be used to gather and store data that is not collected by default. You can create reports or queries to work with this additional data. Extensions allow for unlimited customization of SAP Sourcing to enable you to meet your enterprise's specific needs.
Extensions provide a system-wide mechanism for extending SAP Sourcing business objects with implementation-specific properties. For example, one implementation might require that each supplier object track the last date that the supplier's nondiscrimination policies have been certified. Another might require that each supplier object track a list of ISO certifications. Historically, implementers have achieved this level of customization by editing the schema and code of an application product, introducing material issues that must be revisited with each subsequent release upgrade. SAP Sourcing provides the flexibility to extend without the requirement to edit the product code or schema. This enables the customization to meet the implementation requirements without increasing the cost of subsequent release upgrades.
In addition to tracking implementation-specific data fields, extensions can be combined with two other SAP Sourcing customization features - Query Definitions and Value List Types and Values - to enable additional mechanisms for organizing documents. For example, a value list might be defined with codes identifying a specific categorization of sourcing events. An extension attribute containing a required value list value from the new list could then be added to Auction and RFx sourcing documents. Finally, a query can be developed for searching or sorting available sourcing documents based on the new extension value.
Many types of extensions are supported, including text fields, numbers, checkboxes, drop-down lists, and object references.
Note
The lack of sell-side visibility validation is a known limitation with respect to extensions. It is recognized that it is possible to create extensions for the sell-side that cannot be viewed or edited, due either to security considerations or to lack of accessibility, given the absence of sell-side pickers.
This section describes how to create and edit an extension definition.