The UMSITW concept asserts that subjective awareness is what it is like to be the proceess of updating the model of self-in-the-world 
which has been created within the brain of each individual. The model exists and the continual updating of it occurs as a primary survival mechanism of the individual.
The model constitutes a navigational device by means of which the self - as a living body in the first instance - keeps track of where it is within its physical and social environments. The individual is able to compare outcomes of behaviour with what was planned or predicted, assess any discrepancies, and amend current movement plans or other expectations where necessary.
A key component of this theory is that subjectivity - ie an awareness of being, however rudimentary - arises from a reflexive process in which:
the environment is represented,
the "self" is represented, and
currently significant relationships between self and environment are represented.
For us humans there will be a potentially reportable subjective experience, such as we loosely refer to as consciousness, whenever these three representational processes are linked and to the extent that they are linked.
The component elements of the model of self in the world - and indeed all mental contents - are embodied by dynamic logical structures 
within the brain. These, when active, constitute embodiments of relevant information *about* the respective something or other in the world or of the self of the individual *and* have transitive effect within the brain. This means that they affect other DLS in relevant ways and/or cause bodily behaviour by making muscles move in the right way at the right time.
DLS exist and affect the rest of the world, and there is no reason whatever for assuming they cannot represent or embody any thought that has occurred to a human being on Earth.
This accounts for why we can have dreams at night, including lucid dreams, and why we can have hallucinations, near death experiences and so forth.
UMSITW is fairly compatibe with David Chalmers' Functional Computational Equivalence idea but requires that "functional" really mean what it says. In other words, all discussion of ineffability notwithstanding, the effective outcome is what counts so that similar inputs - physical experience - will result in the same outputs/behaviours and the same, spontaneous, reports of personal subjectivity.
Philosophical mind games, of which the most extreme are the mathematical ontologies of Max Tegmark and Bruno Marchal, and popular sci-fi as exemplified in movies such as the "Matrix" trilogy or "The Thirteenth Floor", all tend to assume that complete emulation is possible in principle. UMSITW however holds that the essence of what is subjectively reported as consciousness is what-it-is-like-to-be the model of self in the world, or more specifically the updating of the model. That is to say the ""quality"" of the experience is "precisely" what it is like to be the of
the model of the moment.
Matrix-like theories suffer from a burden of proof concerning the belief that all aspects of what is occurring within a human brain "can" be modelled within an alternative computational system. Statements to this effect are assertions of faith only and all rest on beliefs that such modelling can surmount the limitations of digital algorithms attempting to emulate analogue processes, for example:
favourite analogy for the interaction of all the little ion channel currents with the electromagnetic fields is the mutual interaction of small scale vibrations in domestic water valves and the large scale resonances of the piping.
- the truncations of digital numbers will almost certainly cause unpredictable, non linear, excursions from the natural patterns of massively recursive signalling processes which occur in the brain, and
- synergies and modulations within the brain arise from the proximity and overlap of physical processes such as ion channel currents across cell membranes and larger scale electrostatic and electromagnetic field changes.
A key understanding here is that *the model exists* and like all models all things
it has to "be" somewhere now. The updating model within the brain is thus limited by its medium and any of it's "emulations" will be limited even more so. For those of us with a sense of humour it is worth meditating now and again on the likely dimensions of any system intended to emulate one or more human minds. I favour gravitational collapse and implosion as the greatest limiting factor.
From a practical point of view it is highly unlikely there will ever be any real *emulations* of the human mind, but there almost certainly will be some very creative artificial intelligences coming into being in future. Maybe there will be millions of them or maybe just one in each self sustaining ecological/economic community. Whatever,they will not be human minds but they will surely demand, and get, the vote!