  We predict a sequence of magic-zero wavelengths for the Sr excited $5s5p~
^3P_0$ state, and provide a general roadmap for extracting transition matrix
elements using precise frequency measurements. We demonstrate that such
measurements can serve as a best global benchmark of the spectroscopic accuracy
that is required for the development of high-precision predictive methods.
These magic-zero wavelengths are also needed for state-selective atom
manipulation for implementation of quantum logic operations. We also identify
five magic wavelengths of the $5s^2\ ^1S_0 - 5s5p\ ^3P_0$ Sr clock transition
between 350 nm and 500 nm which can also serve as precision benchmarks.
