Captioning Standards: Captioning Music

I was watching the live captioning done by the completely amazing CART by Karyn of Tennessee Captioning on Sunday, when I noticed that she uses the double-eighth note (♬) in front and back of each line. This was more noticeable to me, since the Android Browser displays the eighth note (♪) and NOT the double-eighth.

So I watched CMT this morning, sound muted, cc on. I’m guessing that CMT doesn’t require particular standards.
CMT Sample of Music Captioning Showing Speaker Id, Case, and denotation
I found:

1 Mixed Case, 2 UPPERCASE

1 (eighth) notes at the end of each newline, 2 had notes at the end of a full caption

Occasionally described
denoted by 2 eighth notes (1 without spaces, 2 with)
None kept the notes up for the duration of the instrumental only.

I use the DCMP Captioning Key as my standard, knowing of no other.

From DCMP Captioning Key Special Considerations:

Caption lyrics with music icons (♪). Use one music icon at the beginning and end of each caption within a song, but use two music icons at the end of the last line of a song.

For background music that is not important to the content of the program, place a music icon in the upper right corner of the screen.

A description (in brackets) should be used for instrumental/background music or when verbatim captioning would exceed the presentation rate. If known, the description should include the performer/composer and the title.

What say ye?

I use:
-Mixed Case
-Single Eighth note at the beginning and end of each line
-Double Eight note for instrumental (with artist/title), although 2 eighth notes with a blank seems more semantically correct.