|The DITA documentation process / File and folder naming conventions|
Special characters must not be used in file names.
Using special characters in file names may cause some problems or errors in some authoring and publishing tools. Special characters in this context means symbols, typographical characters, punctuation characters, spaces, diacritical characters, and non-Latin characters.
You must treat file names as though they are URIs, and follow the IETF syntax conventions for URI naming.
Refer to IETF Uniform Resource Identifier (URI): Generic Syntax for the comprehensive URI guidelines.