Available to Instance and Context objects and used to pass data between library and plug-ins.
Data is primarily gathered during Collection and used during subsequent plug-ins, such as Validation and Extraction. Data can also be used as a means of messaging across plug-ins.
See Tale of Three APIs for more information.
Data members are using mixedCase.
The motivation is to separate between what is Python and what is Pyblish data.
Data of any type may be added, including complex objects.