Defined exposing SCTE 27 subtitles with DataCue

Changes to use DataCue for exposing SCTE 27 subtitles. This involves changes in: item 3 - setting kind, item 5c - subtitle cues
CEA708 and SCTE27 are rendering specifications. Is the answer to define CEA708Cue and SCTE27Cue that refer to these specs for how to render?