The TClient class is the class that glues all other MML classes together into one usable class. Internally, quite some MML classes require other MML classes, and they access these other classes through their “parent” TClient class.
An image tells more than a thousands words:
And the class dependency graph: (An arrow indicates a dependency)
The client class does not do much else except creating the classes when it is created and destroying the classes when it is being destroyed.