The slab turbulence model is motived by Mariner 2 measurements,
indicating that the solar wind is dominated by
outward propagating Alfvénic turbulence (Belcher & Davis
1971; Tautz & Shalchi 2013). Together with a second, twodimensional
contribution, this gave rise to the composite turbulence
model (Bieber et al. 1996; Matthaeus et al. 1990; Rausch
& Tautz 2013). In numerical simulations, in contrast, Alfvénic
modes exhibit a scale-dependent anisotropy consistent with the
Goldreich-Sridhar (1994,1995) model. Nevertheless, the classic
slab model remains attractive, especially for analytical investigations,
thereby allowing one to isolate specific effects.