Code details

The code is namespaced ; main namespace name is g5.
Code is PSR-4 (namespace hierarchy corresponds to directory hierarchy, like in java).
Top-level namespace (g5) is located in src/.
Another top-level namespace is used (vendor), located in vendor/.
The code does not use composer or other dependency manager, vendor code is copied in vendor/ directory and versioned with the program.

All transformations on data are done in namespace g5\commands.

Association CLI - executed code

The command line interface (CLI) is handled by run-g5.php.
The code uses the parameters given to the CLI to find a class of namespace g5\commands implementing the Command interface.
For details about this mechanism, see comments of class g5\app\Run.

Example: 
php run-g5.php ertel sport look date
triggers the execution of 
g5\commands\ertel\sport\look::execute(['date'])

One exception

This mechanism proved to be sufficient for most cases. It is convenient because it permits to add new commands which can be used directly without having to change a configuration, but couldn't fill the need to handle Gauquelin files of series A. For example, to have the ability to issue commands like
php run-g5.php gauq A1 tmp2db
php run-g5.php gauq A2 tmp2db
would impose namespace gauq to have a sub-namespace A1 and a sub-namespace A2 etc.

So if the first parameter is gauq, the association between the parameters given to the CLI and the command to execute is handled by g5\commands\gauq\GauqCommand.