What do the dashed lines separate in the debug navigator?

Question

Looking at:

I can't understand why are things grouped together between dashed lines.

_{I cropped the screenshot to remove method named I didn't want to share. But this screenshot is entirely from Thread 1 Queue : com.apple.main-thread (serial)}

I already thought of the following three but all seem to be incorrect.

• It's separated by classes. Not true: different classes were on the same side of dashed lines.
• It's separated by directories. Not true: files that were both in RxSwift directory were on different side of a dashed line.
• It's separated by modules. Not true: files from a pod and my own code were on the same side of a dashed line.

I also looked at: Examine threads and stacks in the Debug navigator but didn't find information on how they're grouped.

Answer 1

_{Got this answer from a senior dev named Daniel Kennett on Slack.}

There are lines here that are collapsed (look at the numbers) new messages

You can click a button down in the filter field at the bottom to have it expand the missing lines in the trace