What is the PHP "debug pack" for?

Thanks for the replies people.

What, so you are saying there are so many developers that they put the debug version in public view?

Or, is this like when Firefox crashes, you get this dialog box appearing saying “report this?”.

If the latter was the case, then shouldn’ more of us be doing the equivalent of “report this?” ( though, granted its more likely to be “send us the content of the last php error”, or “send us the content of your cachegrind file” ).

Would we be good community members to download the debug version? And what action should we take.

Or is it the case that - if you have to ask then clearly you don’t qualify.

Comments?

Edit:

Can anyone who uses the debug version tell us what difference using that version makes when you are using it?