[en] The fundamental question which the discovery of the T(9.4) raises is the relationship of the new quark, supposing that this is the proper interpretation of the resonance, to the four previously known quarks. The answer to this may come only when the new e⁺e^- machines are completed and conduct detailed studies of the decay patterns of the new pseudoscalars (let us call them D's) which are expected by analogy to the charmed system. Since such experiments are still some time off and since the identification of actual decay modes may well be further off, there is plenty of time for theorists to speculate without fear of being contradicted by real evidence. For nearly all theorists, such speculation means considering some gauge group which, after spontaneous symmetry breaking, yields a unified theory of weak and electromagnetic interactions. After a gauge group is chosen, there is still much freedom in assigning the fermions of the theory to multiplets. These choices are constrained by our knowledge of weak interactions: the standard V-A phenomenology must be reproduced for the charged currents and what is known of the neutral currents must be accounted for as well

[en] The D⁺ and D^- lifetimes has been directly measured with a silicon telescope to be 9.5sub(-1.9)sup(+3.1) 10¹³s. Detailed discussion of corrections is given

[en] Charmed meson pairs have been photoproduced coherently on an active multilayer silicon target in the energy range 80-150 GeV. D antiD and F antiF state have been identified and an estimate of the lifetimes is given

[en] The present experimental information on the spectroscopy and decay properties of charmed mesons is summarized

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[en] A review is given of the nonleptonic decays of D mesons. Included are measurements of the psi(3772), the accurate determination of D masses and their consequences, and inclusive measurements and tagged events. It is noted that the distinction between the above designated events is that in the former one detects a D decay and ignores the remainder of the event, while in the tagged events a D decay is detected and also the remainder of the event is studied. 39 references

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[en] Because the branching ratios of the purely leptonic modes of D meson are small compared to the semileptonic decays, it is suggested that the decay D → K + l + ν might be used to deduce the value of F/sub D/, the weak decay constant of D meson. 17 references

[en] Several tests that have been proposed to determine the various components (nonstrange, strange and gluonic) of the pseudoscalar mesons eta-eta'-iota are briefly reviewed. The constraints provided by these tests do not allow an unambiguous determination of the strange components of the eta' and iota mesons. It is suggested that this would follow from the experimental measurement of the branching ratios BR(F^+- → eta'π^+-) and BR(F^+- → iotaπ^+-). The decay F^+- → iotaπ^+-, in particular, would be crucial to understand the physical nature of the iota-meson or, differently stated, to establish (or to disprove) the validity of the eta-eta'-iota mixing