Basically a module consists of one folder below the folder named "images" in OmniBoot-root. A module can be added and removed just by inserting or deleting this folder. It will show up or disappear automatically from the menu-system. If the om-script is run subsequently with the "cr" or the "ch" option the module is added or removed entirely to or from the menu system and the content table. Please always leave the module "[base]" in place - if you remove it, its menu-entries will still show up despite being disfunctional. Don't add any module named "base", the script will just refuse to work for it would mix it up with "[base]". Also "status" is forbidden as module-name and no blanks or special national characters (e.g. Umlauts) are allowed in folder- or filenames.
So if you wish to reduce the size of your personal edition of OmniBoot just chose some modules and remove/delete their folder within the folder named "images", possbily previous to running the initial build to also save the time for downloads.
Every module-folder contains a folder named "menu". There you find a configuration file for the menu-system starting with "mod_" and the module-name. There is also a configuration file for the om-script which is needed for the creation of OmniBoot (named "modulename.cfg"), respectively the integration of that specific module into the menu-system and its correct configuration for languages and pxe-services if needed.
The purpose of packing the modules in iso-files: They work standalone too, can directly be burned and don't need OmniBoot to boot. Yet this stand-alone version features a little toolbox (memory testing, netbooting etc) and if available a language selection submenu.
View the content tab to see the current versions and menu-locations. Some modules have their version info linked to a package list (in that content table) and some their release-date to a direct download-link.