Objective C Comment Tags

Hi
While writing a software one has to work across multiple files and its easy to forget those mental notes we make to revisit certain parts of the code. Objective C and Xcode provide some niftly tags to mark these areas in the code. The Tags are:

1) TODO
Syntax:
// TODO: add function call

2) FIXME
Syntax:
// FIXME: remove view and add image

3) ???
Syntax
// ???: How does this work?

4) !!!
Syntax
// !!!: to be verified

Via: http://iphonedevelopertips.com/xcode/xcode-fixme-and-todo.html