VNX Filer FileSystem API query not returning NMFS file system information

Greetings,

We are in process of adding support for VNX filer in our SRM solution. To collect the data from VNX filer, we rely in XML APIs exposed by the device. In order to collect File System information, following query is being used -

http://www.emc.com/schemas/celerra/xml_api \" xmlns:meta=\" http://www.emc.com/schemas/celerra/xml_api_meta \" xmlns:xsi=\" http://www.w3.org/2001/XMLSchema-instance \" xsi:schemaLocation=\" http://www.emc.com/schemas/celerra/xml_api \">

This query returns all the filesystem on the filer except the NMFS filesystems.

Can some one throw the light on why NMFS file systems are not returned by the XML API ?