\letter A `AlmostCrystallographicDim3', 7 `AlmostCrystallographicDim4', 7 `AlmostCrystallographicGroup', 7 `AlmostCrystallographicInfo', 9 `AlmostCrystallographicPcpDim3', 8 `AlmostCrystallographicPcpDim4', 8 `AlmostCrystallographicPcpGroup', 8 \letter B `BettiNumber', 5 Betti numbers, \indexit{5} `BettiNumbers', 5 \letter D Determination of certain extensions, \indexit{5} \letter E Example computations I, \indexit{12} Example computations II, \indexit{12} Example computations III, \indexit{13} \letter H `HasExtensionOfType', 6 `HolonomyGroup', 8 \letter I `IsAlmostBieberbachGroup', 5 `IsAlmostCrystallographic', 5 `IsomorphismPcpGroup', 8 \letter M More about almost crystallographic groups, \indexit{3} More about the type and the defining parameters, \indexit{9} \letter N `NaturalHomomorphismOnHolonomyGroup', 8 \letter O `OrientationModule', 5 \letter P Polycyclically presented groups, \indexit{8} Properties of almost crystallographic groups, \indexit{5} \letter R Rational matrix groups, \indexit{7} \letter T The electronic versus the printed library, \indexit{10}