EM= EMI filter, it was a "T" shaped filter that has horizontal branches composed by two FB and a central vertical branch composed by a capacitor example: https://www.electrokit.com/uploads/productfile/41013/41013667.pdf it's a 3°order LC low pass filter, but in recent motherboards (C64C also...) was used a cheaper components that hasn't the beads and it's only a wire that cross in a side of a capacitor...
Parts in the schematics
