The allow element defines an allowed IP address or range of addresses, and contains an ip attribute, composed of an ip value and a mask value, separated by a slash (/).
The Gateway ANDs each incoming IP address with the allow mask. Then it ANDs the ip value in the allow element with the mask. If the results of the two ANDs match, the Gateway allows the incoming IP address to access the database.
The allow element can appear only as a child of an ipfilter element. You can use as many allow elements as needed in an XML IP restriction document. When multiple allow elements appear in a document, only one match is necessary to allow the session to proceed.