What do outlined reads in IGV represent?

Question

[jsneaththompson]

I've been looking at some of my NGS data in IGV, and I've found some reads that aren't given a block colour, but instead are outlined in blue. I can't seem to find an answer in the IGV docs, does anyone know what this colour scheme signifies?

I've attached a link to a picture by way of example

Answer 1

[lakhujanivijay]

A black outline indicates that the selected read has no mate. Source here