What does green checkmark mean on NGL?

so what does the green check mark mean on NGL so if you go to your inbox on NGL app you can basically see three types of letter icons gray like colored red icons gray and then their gray icons with a green tick in the top right so basically red means that it's just an open NGL message when I open it up it becomes gray so gray icon means I open up the message and then when I go to the message and I tap reply basically from here you can just reply to to the message and then after you reply to the message on Instagram story you will get this green tick in the top right so basically green tick green check mark on angel means that you have replied to the NGL message