  Extended or generalized similarity is a ubiquitous but not well understood
feature of turbulence that is realized over a finite range of scales. ULYSSES
spacecraft solar polar passes at solar minimum provide \textit{in situ}
observations of evolving anisotropic magnetohydrodynamic turbulence in the
solar wind under ideal conditions of fast quiet flow. We find a single
generalized scaling function characterises this finite range turbulence and is
insensitive to plasma conditions. The recent unusually inactive solar minimum
-with turbulent fluctuations down by a factor of $\sim 2$ in power- provides a
test of this invariance.
