See attached screenshot. 'Series 1' projectors have been sold until 2009/2010 - they are SMPTE compatible, but do not support all SMPTE features. 'Series 2' is what most cinemas use now - all current 2k and 4k DLP projectors (so, except Sony). The subtitle display code in series 1 and series 2 is from TI and all projectors using the same software level support the same feature set. There are now a few so called 'series 3' systems out in the market (e.g. Barco ICMP), but while 'series 3' seems to establish a category, they are not made by a single OEM like TI for series 1 and 2, but every projector/server manufacturer creates their own design, so, no common features in series 3. Some servers allow to render subtitles server side (essentially, burning them into the image that is then transferred to the projector). For some of the mentioned series 3 systems, there is no distinction between 'server side' and 'projector side' anymore (same as e.g. for Sony systems).

No one so far published a feature matrix for these devices, but there is a current report:

http://www.isdcf.com/meeting/Theatrical_Subtitle_Presentation_Quality_V5_20181017.pdf

So, Z position it seems can be used safely, but not dynamic Z position. Wether some systems simply ignore it or crash, I have no idea.

• Carsten