File extension mapping allows users to access members of z/OS conventional MVS PDS or PDSE data sets on the z/OS host that are mapped from client machine files that contain file extensions. File extension mapping also allows the selection of text or binary processing for members of z/OS conventional MVS data sets and z/OS UNIX files.

Each PDS or PDSE data set on the host can only be mapped with one unique file extension. For example: IBMUSER.TEXT(M1), IBMUSER.TEXT(M2) will map to m1.txt, m2.txt under directory ibmuser.text on the client machine. This capability allows client machine tools such as editors and compilers, to process host files remotely without modification. There are site and processing attributes and an operator command that are associated with the file extension mapping.

The rules for file extension mapping are contained in a data set called a side file. The side file consists of two sections: NFS.MAPPING and NFS.MAPPING.MAPPED.

Section NFS.MAPPING is used to define file extension mapping for z/OS conventional MVS PDS/PDSE data sets. The client user can specify the fileextmap attribute to turn the file extension mapping on and the nofileextmap attribute to turn the file extension mapping off. Section NFS.MAPPING.MAPPED is used to specify whether text or binary processing is performed for file extensions of z/OS conventional MVS data sets and z/OS UNIX files. The client user can specify the mapped attribute to specify when a mixed set of data types is to be processed. For z/OS conventional MVS data sets, the maplower and nomaplower attribute controls the mapping of lower case files names to upper case when accessing files on z/OS.

You can establish a default side file, with the default rules for file extension mapping, by specifying the sidefile(dsname) attribute in the attributes data set. A client user can also specify this attribute on a mount command to override the default side file name, as shown in the following example:

[C:\] mount z: mvshost1:"user1.pds,sidefile(hlq.nfs.mapping)"

The side file specified at the mount command will be searched first followed by the default side file. The system administrator can specify the maximum space available for side files using the site attribute sfmax(n). The mapfile operand of the modify command can be used to have a side file read again and rebuilt without stopping and restarting the server or remounting of mount points. A sample mapping side file is provided as GFSAPMAP in the SYS1.NFSSAMP library. See Entering operands of the modify command for the z/OS NFS server, Processing attributes syntax, and Site attributes syntax for more information.