The library urx contains the data structure and the API.

The data structure represents raw data. This can be a file or data structures in C++ / MATLAB / Python formats.

The API includes C++ functions exploiting the data structure, as well as Python and MATLAB interfaces.

The library loads a file with the same major version number but imports a file with an older major version number.

Version numbers follow X.Y.Z format where:

• X: major version,
• Y: minor version,
• Z: patch version.

A major version change occurs when there is a compatibility break in the data structure and possibly the API.

A minor version change occurs when a feature is added or deprecated in the API, or when a field in the data structure is deprecated. Deprecated elements may be removed when the next major version is released.

A patch version change occurs when there is a modification in the API that neither adds nor removes features (such as a bug fix).

When the data structure is loaded by a library with the same major version but a different minor or patch version, the data structure version is updated in memory, but the original file is preserved. Note that when the loaded data structure is saved to a file, the version written will be the new version.

Case	Change
Change in data structure	Major
Optimization of read/write time	Minor (if a new function or parameter is added to a function), Patch (if C++ function signatures and Python/MATLAB interfaces remain unchanged).
Better installation tool	Minor (e.g., if a MATLAB file is missing), Patch (if no new feature is introduced).

A version of the urx library can only read data from the same major version via the load method.

Use the import method to read a urx file with a lower major versions. As a reminder, any modification to the data structure requires a major version change.

If the data structure to be read has a higher major version than the library, you must either update your library/software or use the external conversion utility available in a more recent version of the library.

This utility allows you to upgrade or downgrade versions. A final report will indicate any potential incompatibilities.

Case	File version	Library version	Behavior
Major	1.2.3	0.x.x	Cannot read file. Ask the user to update the software or convert the data via the external utility from a more recent version.
Major	1.2.3	2.x.x	Cannot read file. Ask user to import urx file.
Patch	1.2.3	1.2.x	Compatible
Minor	1.2.3	1.0.0	Compatible
Minor	1.2.3	1.5.0	Compatible