Remote-to-local file mapping

When you define a remote system, you map (associate) the lowest level qualifier in each MVS™ data set name to a file name extension for the related workstation file. IBM® Explorer for z/OS® includes a set of defined remote-to-local file mappings. The **COBOL file mapping, for example, maps MVS files with a low-level qualifier COBOL to workstation files with the .cbl file name extension.1


A mapping indicates how IBM Explorer for z/OS processes file transfers between z/OS and the workstation; specifically, the mapping indicates whether file transfers are based on an exchange of text (in which case ASCII/EBCDIC conversions occur) or on an exchange of binary data. A mapping also helps you to know, at a glance, the general purpose of a particular file.

If you use the same low-level qualifier for several data sets, the same mappings affect file transfers for each of those data sets. Given the mappings that are included in IBM Explorer for z/OS, for example, you can transfer members of the partitioned data sets USER01.COBOL and USER01.TEST.COBOL to and from workstation-based files that have the extension .cbl.2

You can see remote-to-local file mappings in the z/OS File System Mapping view of the RSE perspective perspective. The following screen capture shows this view.

You can customize these mappings to match the naming conventions on your remote system either through the z/OS File System Mapping view or on the Mapping page of the Properties window. For more information about customizing these mappings, see Mapping data sets and partitioned data set members. For more information about the properties of file mappings, see the remaining sections of this topic.

z/OS file system mappings

Workstation file extension

The type of a file is indicated by its workstation file extension. In the mappings that are shown in the screen capture, a .cbl extension, for example, is considered to be a COBOL source file. Each file can have only one file type. JCL with embedded COBOL source, for example, is not supported. The default workstation file extension for a new mapping is undefined.

Transfer mode

The transfer mode can be either text, indicating that a conversion between ASCII and EBCDIC occurs, or binary. The default transfer mode for a new mapping is text.

Code page

Each file can have only one code page, but you can specify a group of files as having the same code page. When you specify code pages, specify both a local and a host code page and keep them consistent. The default host and local code pages for a new mapping are inherited from the system properties of the remote and local file systems.

For a list of supported host code pages, see Supported host code pages. The availability of local code pages is based on the text file encodings that are supported by the Eclipse text editor. Be sure to specify code pages to be consistent with the compiler settings of your files.


If a file matches more than one file mapping, the mapping with the highest priority is the one that applies. In the following example, a file named MYUSERID.SOURCE.COBOL matches both of these file mapping definitions. Because the **COBOL mapping has the higher priority, its properties are applied during a file transfer between the remote and local systems. It is transferred to the workstation with these file transfer properties: .cbl file extension, text transfer mode, inherited workstation code page.
Mapping Criterion Workstation File Extension Transfer Mode Host Code Page Local Code Page Priority
**COBOL .cbl default (text) default (inherited) default (inherited) 1
**COBOL* default (undefined) binary default (inherited) default (inherited) 2

1 For IDz users, you can define an alternative logical NOT symbol in a file mapping definition. For more information, search for Specifying an alternative logical NOT symbol in IDz KC.
2 In the workbench, a preference that is related to the z Systems® LPEX Editor causes workstation-based files of a particular type to be treated in a particular way. In accordance with this preference, for example, a file of type .cbl is presented with the syntax highlighting that is appropriate to a COBOL source file. However, when the editor processes a z/OS-based data set, the mapping of a qualifier (like COBOL) to a file name extension (like .cbl) determines how the data set is processed.