  The Finsleroid-Finsler space is constructed over an underlying Riemannian
space by the help of a scalar $g(x)$ and an input 1-form $b$ of unit length.
Explicit form of the entailed tensors, as well as the respective spray
coefficients, is evaluated. The involutive case means the framework in which
the characteristic scalar $g(x)$ may vary in the direction assigned by $b$,
such that $dg=\mu b$ with a scalar $\mu(x)$.
  We show by required calculation that the involutive case realizes through the
$A$-special relation the picture that instead of the Landsberg condition $\dot
A_{ijk}=0$ we have the vanishing $\dot{\al}_{ijk}=0$ with the normalized tensor
$\al_{ijk}=A_{ijk}/||A||$. Under the involutive condition, the derivative
tensor $A_{i|j}$ and the curvature tensor $R^i{}_k$ have explicitly been found,
assuming the input 1-form $b$ be parallel.
  Key words: Finsler metrics, spray coefficients, curvature tensors.
