n00b BASEPATH question: From where is the BASEPATH value obtained?

[eluser]Unknown[/eluser]
I probably should have mentioned that I am using CI_VERSION 1.7.2

My index.php does not have the lines you mention. So, in short, CI is looking for my constants.php at the BASEPATH:

root/Library/Server/Web/Data/Sites/Default/php/web_production

when it SHOULD be looking in the BASEPATH:

root/Volumes/boot2/Library/WebServer/Documents/php/web_production

I am unable to decipher from where this derived in the index.php file. Here is my index.php on Dropbox:

https://www.dropbox.com/sh/oukr082diix9i...xphpCI.txt