My book shows a red highlight on a sentence. What does that signify?
I see a yellow highlight on the sentence that is being read currently.
But now I am seeing a red highlight on one sentence. I did not make it. I tried to double-tap on the sentence previous to it, and played @Voice. When the yellow highlight comes on the red highlighted sentence, it shows a yellow highlight with a red border. And when the yellow highlight moves on to the next sentence, the red highlight re-appears.
What does this red highlight signify?
Is this a useful feature that I can exploit? For example, marking the book with a permanent highlighter?
I didn't find this description in the help manual embedded with @Voice.