  We discuss the concepts and the framework of the renormalization procedure in
regularization-invariant momentum subtraction schemes. These schemes are used
in the context of lattice simulations for the determination of physical
quantities like light quark masses. We focus on the renormalization procedure
with a symmetric subtraction point of a quark mass and discuss its conversion
from the RI/SMOM scheme to the MSbar scheme. A symmetric subtraction point
allows for a lattice calculation with a reduced contamination from infrared
effects. The perturbative series for the resulting matching factor at
next-to-leading order is better behaved for the symmetric momentum
configuration than for the exceptional one which can decrease the uncertainty
in light quark mass determinations.
