This snip is from a professional subtitle source. The percentages and whatnot on the lines all print to screen.
Of course the cleff notes and images for song belong on the clip but the primary lines with
all these instructions also print to VLC.

Who can say what they represent? I'd suspect that Subtitle Edit's 'fix all common errors' option
might be able to delete them for easier viewing but I'm guessing.

Clip below,,,


1
00:00:00,966 --> 00:00:05,800
47.5% line:5% size:42.5%
♪♪

2
00:00:05,800 --> 00:00:08,000
10% line:5% size:80%
-Next on "Great Performances"...

3
00:00:08,000 --> 00:00:12,266
27.5% line:5% size:62.5%
-♪ I am gorgeous ♪

4
00:00:12,266 --> 00:00:14,233
12.5% line:89% size:77.5%
-...six-time Tony Award winner

5
00:00:14,233 --> 00:00:16,866
10% line:83% size:80%
and two-time Grammy Award winner
Audra McDonald