From the OASIS Naming Directives at
http://docs.oasis-open.org/specGuidelines/ndr/namingDirectives.html#nameCharacters 3. Name Characters for Files and Directories For any filename or directory/folder name, TCs must use only the sixty-four characters from among alphanumerics [A-Za-z0-9] and the two punctuation characters: "." (PERIOD), and "-" (HYPHEN)" — that is, any upper-case character, lower-case character, Arabic numeral/digit, FULL STOP [decimal 46], and HYPHEN-MINUS [decimal 45]. These name character restrictions must be adhered to for all files/directories associated with approved Work Products and any candidates for TC approval ( e.g. , Working Drafts). The rules should be followed in all other contexts where OASIS tools and publication venues support the constraints. The UNDERSCORE character ("_") may be used in filenames and directory names where an application (unavoidably) generates this character, but in general, use of HYPHEN to mark juncture is preferable; the UNDERSCORE character may be visually confused with SPACE or an underline-effect in some predictable publication contexts. An UNDERSCORE must never be used in a filename or directory name that is used in a document URI — that is, a primary URI reference published as a document cover page URI ( i.e. as required for identification of a Work Product as a whole or for identification of a separately-titled prose Part in a Multi-Part Work Product). Best, Kris Kristen James Eberlein Chair, OASIS DITA Technical Committee Owner, Eberlein Consulting LLC
kris@eberleinconsulting.com Skype: kriseberlein; voice: +1 (919) 622-1501