This section changed and now matches the requirements for fire-rated assemblies. You need to “IDENTIFY” your supports (ceiling wires) that you install for support of your wiring methods.
These are the ones that you install to support your EMT, MC or other types of wiring assemblies. The wires that are installed to support the fixtures are not based on the ELECTRICAL CODE and do not need to be identified. The ones installed for the support of the fixture come from the manufactures’ installation requirements and should be installed by the ceiling installer to make sure they are installed properly. The only requirement in the NEC for a fixture that is installed in a grid type ceiling system is that the fixture be screwed, clipped, or riveted to the grid, see 410.36(B).
Till Next week Work Safe and be Safe!