For me MIRRORLESS means every camera without slapping, full reflective mirror.
Fixed Semi-reflective mirror camera still have a mirror, so it could be named SLR, but it is more an hybrid construction between mirrorless and conventional SLR with a quick return mirror.
Plus the patent clearly shows (in section 0015) that "a quick return mirror and a dedicated focal point detection unit are not provided in the camera body."
=> No mirror at all
or
=> Fixed pellicle mirror with either an OVF (like eos RT) or with an EVF (like Sony Translucent, SLT slr)
