It looks like a non-standardized extension of the SRT format.
Normally, SRT doesn’t support either colorization, nor position formatting. For that, you’d need to use ASS.
In fact, these formatting tags appear to have been “borrowed” from the ASS specification. But it is pure luck if they are supported when used within a SRT file.
So it depends on whether these non-standard extensions of the SRT format have been incorporated into the program code which is used on the respective platform for rendering subtitles.
@OttoKerner what is strange to me, is the fact that the Plex web client does support these formatting tags between curly braces and correctly renders the color and position.
Does Plex iOS use a different rendering platform compared Plex web?
See the last two sentences of my previous post.
It is pure luck that they are working in the web app. It is only due to the fact that this software library happens to support also (a part of) the ASS format.
On iOS something different is used to render the subtitles, so this “quirk” is not there.
