I see it as "above the line" is must-do items before movement (Ext power removed, transponder set, hydraulic panel check for steering, cabin ready for taxi, emerg lights armed). I guess the rest is stuff that can be done after, especially after FFOD checks (can't set CTOT, autocoarsen, and ice protection until after checks are complete)... during the winter, we made sure to do "above the line" then leave the gate to do checks only so the rampers could go inside and warm up