Part 97.3 "Definitions" defines: "SS. Spread-spectrum emissions using bandwidth-expansion modulation emissions having designators with A, C, D, F, G, H, J or R as the first symbol; X as the second symbol; X as the third symbol. "
Title 47 Sec. 2.201 is the relevant section formally defining these symbols. It can be found on the ARRL website. For a signal to be officially considered Spread Spectrum by the FCC, it would have to meet a very specific description, or maybe I should say it should not meet the other specific definitions of emissions. After my reading of 2.201, I don't think that ROS or Chip64 could be "officially" defined as Spread Spectrum. And, the response from the FCC doesn't provide any FCC position or interpretation of ROS, and further says "The Commission does not determine if a particular mode "truly" represents spread spectrum as it is defined in the rules." Just my thoughts, Max NN5L