When you specify security(exports) in the attributes data set, the NFS server checks the client IP address against the exports list, which is generated from the exports data set, to determine whether or not a mount is to be granted. The NFS server also checks the requested directory (or high-level qualifier) to be mounted. For z/OS UNIX data, it also checks the UNIX permission bits before granting file access to a client user. See Figure 1 and Table 1 for information on permission checking.