Preserving round-trip integrity of MVS™ files

The JCL Editor ensures that characters converted from one encoding (code page) to another and then back to their original encoding remain unchanged.

When you edit a remote file with the JCL Editor, it looks like you are editing the file directly on the remote system. In fact, the file is downloaded to a cache in the local workspace, then saved to the remote system when the editor session ends. This process of downloading to the workstation and then uploading to the remote system involves converting the file contents between the remote EBCDIC-based encoding (for example, IBM-037) and the local ASCII- or Unicode-based encoding (for example, Cp1252 or UTF-8). z/OS Explorer uses code page mappings to determine the remote and local encodings, as described in Remote to local file mapping.

Certain characters do not translate precisely from one code page to another and then back again, depending on the code pages involved. To ensure round-trip integrity, the editors open remote files in browse mode so that you cannot corrupt the file by saving it back to the remote file system. In addition, the characters that cannot make the round trip with integrity are highlighted.