1.6 Versioning and Localization
This document covers versioning issues in the following areas:
Structure Versions: There are two versions of the compound file structure, version 3 and version 4. These versions are defined in section 2.2. In a version 4 compound file, all features of version 3 MUST be implemented.
Localization: There is no localization-dependent structure content in the compound file structure. In the implementation, all Unicode character comparisons MUST be locale-invariant and all timestamps MUST be stored in the Coordinated Universal Time (UTC) time zone.
Implementations MUST return an error when encountering a higher version than supported. For example, if only a version 3 compound file is supported, the implementation MUST return an error if a version 4 compound file is being opened.