Request is a property in the portal.properties file, which is the default configuration file for Sun GlassFish Web Space Server. You can override this property using portal-ext.properties file.
Portlets that have been configured to use private request attributes in liferayportlet.xml may still want to share some request attributes. This property allows you to configure which request attributes will be shared.
Set a comma-delimited list of attribute names that will be shared when the attribute name starts with one of the specified attribute names. For example, if you set the value to hello_, world_, then all attribute names that start with hello_ or world_ will be shared.