UDF Supported Characters:
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Volume identifiers can be a maximum of 30 characters and must contain only alphabetic characters (A through Z), numeric characters (0 through 9), a hyphen (-), or a period (.). The first character must be alphabetic or numeric, and the identifier cannot contain embedded blanks.

Although not required, you can include one or more directories in the path name. Each element of the path can be a maximum of 254 characters with a total maximum path length of 256 characters. A path name can consist of any of the EBCDIC characters except x00-x3F, xFF, quotation marks ("), asterick (*), less than (<), greater than (>), question mark (?), and backward slash (\).

Source: https://www.ibm.com/docs/en/i/7.4?topic=format-volume-directory-file-names
Date: December 31st 2023