  To explain conceptual gap between classical/quantum and other, hypothetical
descriptions of world, several principles has been proposed. So far, all these
principles have not explicitly included the uncertainty relation. Here we
introduce an information content principle (ICP) which represents the new -
constrained uncertainty principle. The principle, by taking into account the
encoding/decoding properties of single physical system, is capable of
separation both classicality and quanta from a number of potential physical
theories including hidden variable theories. The ICP, which is satisfied by
both classical and quantum theory, states that the amount of non-redundant
information which may be extracted from a given system is bounded by a
perfectly decodable information content of the system. We show that ICP allows
to discriminate theories which do not allow for correlations stronger than
Tsirelson's bound. We show also how to apply the principle to composite
systems, ruling out some theories despite their elementary constituents behave
quantumly.
