Open a script in notepad (right click > edit) and take a look at it. Jeroen has put lots of comments in the scripts, so that you don't need to learn the script language.
/* Zone 1: Place the MFT and some other special NTFS files. */
/* Zone 2: Directories. */
/* Zone 3: files used when booting, and a gap. */
/* Zone 4: files used by the most used programs, and a gap. */
/* Zone 5: regular files and a gap. */
/* Zone 6: spacehog files (less important files that take up a lot of space). */
Zone 4 is new since 4.2.8.