Dope sheet editor. What does the orange line between keyframes mean? I start to use the dope sheet view to see my key frames. But I don't understand why for some I have an orange line and not for others like below. What is the meaning of the orange line between keyframe?
Those orange lines represent a hold: the selected keyframes at each end have the same value, so there is no transformation in between them.
For example:

For unselected keyframes the line connecting equal keyframes will be displayed in gray.