@@ -574,6 +574,7 @@ The
 .B sloppy
 option is an alternative to specifying
 .BR mount.nfs " -s " option.
+
 .TP 1.5i
 .BI xprtsec= policy
 Specifies the use of transport layer security to protect NFS network

@@ -607,6 +608,19 @@ option is not specified,
 the default behavior depends on the kernel,
 but is usually equivalent to
 .BR "xprtsec=none" .
+.TP 1.5i
+.B fasc
+Triggers the clearing of the file access cache as soon as the cache 
+timestamp becomes older than the user's login time. It is supported 
+in kernels 6.4 and later.
+.IP
+NFS servers often refresh their users' group membership at their 
+own cadence, which means the NFS client's file access cache can 
+become stale if the user's group membership changes on the server 
+after they've logged in on the client. To align with the principles 
+of the POSIX design, which only refreshes the user's supplementary 
+group information upon login, the mechanism uses the user's login 
+time to determine whether the file access cache needs to be refreshed.
 .SS "Options for NFS versions 2 and 3 only"
 Use these options, along with the options in the above subsection,
 for NFS versions 2 and 3 only.