In the microlocal theory of sheaves developed by Kashiwara and Schapira, there is the notion of a $\mu$-stratification, which is a stratification satisfying a stronger property ("$\mu$") than Whitney's conditions A and B.
How is this "$\mu$" condition used foundationally in the development of microlocal sheaf theory? Why is it useful to assume a stratification is $\mu$ rather than just Whitney A and B?
