The real, complex, and
quaternionic half-spaces are introduced in certain analogy with the Siegel half-space.
The modified symplectic group acts on the attached half-space in the usual way. At
first properties of these half-spaces considered as symmetric spaces are derived. Then
a fundamental domain with respect to the modified modular group, which consists of
integral modified symplectic matrices, is constructed. The behavior of convergence of
the corresponding Eisenstein-series is determined carefully. The Fourier-coefficients of
the Eisenstein-series are calculated explicitly, whenever the degree is sufficiently
small.