Adding Weird Subtitles

[Sakuya]

Hello. I recently downloaded some subtitles but the file had a SUB file as well as an IDX file. I asked the creator and he said:

"idx short for index. and that sub file shouldn't be a normal one (normal as in you can't see the script if you open the file with an editor) if there is a idx file. Thats because those are images in the sub file and no text.
I'm not in the mood to explain right now why and I doubt you really want/need to know lets just shorten it up: you need both files and both files need to be labeled the same as the videofile to work properly."

So I want to add the subtitles to the video permanently and then to convert the AVI to MPEG for VCD. What should I do about the IDX files and what tutorial should I use? Currently, I'm looking at this one:

https://www.videohelp.com/srtsubsvirtual.htm

If I convert the SUB file to SRT via Subtool, what would happen to the IDX file? I'm not sure what the creator meant by "those are images in the sub file and no text" because my AVI file is still downloading. Any help is appreciated!

[Baldrick]

if you are converting with tmpgenc you can use vobsub(it supports the sub and idx subtitle formats),
https://www.videohelp.com/forum/userguides/153058.php

[Sakuya]

But I still don't get it. If the SUB and IDX files are meant to be used together at the same time?