# Namespaces Tab

Namespaces tab

Namespaces are URIs (Uniform Resource Identifiers) that uniquely identify a set of resources on the Internet. Because URIs can be very lengthy, shorthand aliases called prefixes are typically defined and used in XML files to make the XML more readable.

The Namespaces tab lists all of the namespace URIs and their prefixes in scope for the currently selected activity. Whenever you create a reference to an external property (an element defined in an XSD) whose namespace has not yet been assigned a prefix, the BPEL Designer will prompt you to create a prefix. This can also be done beforehand through the Namespace tab of the Properties sheet for the property by clicking the Assign Prefix button.