What does the output of NSLog exactly mean? [duplicate]

This question already has answers here: Closed 11 years ago.

Possible Duplicate:

NSLog 10b meaning?

I am new to objc and iOS development. And, I have a question about NSLog. As we know, 开发者_运维知识库NSLog will log message like this:

2011-07-16 23:19:35.467 HelloWorld[11166:7c37] say hello to iOS.

Obviously the format is date time ProjectName, but what does the [11166:7c37] part mean?

---

Its a process / thread ID I believe.