  Some properties of numerical time integration methods using summation by
parts operators and simultaneous approximation terms are studied. These schemes
can be interpreted as implicit Runge-Kutta methods with desirable stability
properties such as $A$-, $B$-, $L$-, and algebraic stability. Here, insights
into the necessity of certain assumptions, relations to known Runge-Kutta
methods, and stability properties are provided by new proofs and
counterexamples. In particular, it is proved that a) a technical assumption is
necessary since it is not fulfilled by every SBP scheme, b) not every
Runge-Kutta scheme having the stability properties of SBP schemes is given in
this way, c) the classical collocation methods on Radau and Lobatto nodes are
SBP schemes, and d) nearly no SBP scheme is strong stability preserving.
