As often is the case with mean-field treatments, construction of mean-field effective operators for open-shell references might lead to artifacts. Below we discuss intrinsic issues of SOMF in the case of open-shell references. Note that these problems arise only when the reference, not the target state, have open-shell character. For example, EOM-IP/EA calculations of doublet states using closed-shell references are not affected by this issue, however, EOM-SF calculations using high-spin references are. The analysis is based on considering the second-quantized form of the mean-field spin-orbit operator in a spin-restricted spinorbital basis (meaning that the spatial parts of spin-orbitals φ pα and φ pβ are the same, e.g.