At present, the concept of a digital twin is applied primarily to computer-based representations of technological devices and processes that interact directly with dedicated software systems. Considering that such systems are ultimately designed to meet human or societal needs, in many cases they also involve human users and operators. Unfortunately, in contrast to the technologically based digital twin concept, there is a dearth of available guidance on how human interactors(i.e., digital human twins (DHTs)), should be defined in the context of various digital twin platforms. This is particularly problematic given that humans tend to be much more complex, diverse, and idiosyncratic compared to even the most complex technological systems. Unfortunately, few software designers possess the wide-ranging and complex expertise required to construct adequate models of human interactors (psychology, sociology, anthropology, etc.). The obvious consequence is that many software-based representations of human interactors are highly inadequate. As an initial step towards mitigating this shortcoming, this vision paper proposes a comprehensive framework intended to guide and assist software designers in creating DHTs for their systems. The design rationale behind this model is explained, along with a relatively detailed description of its primary concepts and relationships. The paper concludes with a short discussion of how the model can be used in practice and recommendations for further research work.