How do I list the default installed packages?

I am developing an offline installer for all versions of Ubuntu, and I need Ubuntu's default installed packages list. Is there a way to get this information from any server (web server)? Any script to fetch any Ubuntu version's default installed packages list.

I will give the Ubuntu version, and the script will fetch the packages list.

Note: I need at least a server address. I can write a script for this.

Going off a previous answer of mine, there are manifest files available that should list all the packages included on the CD.

The URLs of the files are fairly predictable but in constant flux (as new releases come out and old ones are killed off) so a good strategy is:

1. Go to http://releases.ubuntu.com/ (for currently supported versions) or http://cdimage.ubuntu.com/ (for other versions, server images, etc.)
2. Pick your spin
3. Pick releases
4. Pick a version (eg 14.04)
5. Pick release (if it has been released)
6. Find the applicable .manifest file.

Note that not all these packages stay installed. On the CD images, you'll also find a file called /capsper/filesystem.manifest-remove which is a list of things to remove after installation. I can't find an online copy of these files on their own.