What does it mean when an eBook platform says it supports the OEBPS?
Unfortunately, it means nothing at all.
The OEBPS explains very clearly what an OEBPS-conformant reading system must accomplish (though not how it must do so). No vendor (that I know of) is yet claiming that their reading system is fully OEBPS-conformant. Not one.
The OEBF does not specify what “supporting OEBPS” means. Anyone can say they “support the OEBPS.” The OEBF does not check on such claims.
“OEBPS support” typically means that the system can handle Basic OEBPS Documents—in other words, plain old HTML—and possibly CSS.
Are reading system vendors dodging important OEBPS implementation issues? Of course they are. Is this confusing to publishers and publishing service providers? Of course it is. The only way to keep them honest is to ask what precisely they mean by “OEBPS support.”
Are OEBPS Publications cross-platform?
Nothing in the OEBPS requires or promotes the use of one computer platform or operating system over another for authoring or for display. Since the specification is open, anyone can program an OEBPS-conformant reading system for any platform, assuming sufficient computing power to handle the tasks involved. (I have heard of, though not seen, GameBoy devices programmed to read Basic OEBPS Documents!) The same is true for authoring and conversion tools; anyone with the requisite skills can create them for any computing platform.
What are all these other formats? .lit, .imp, .rb, and so on? How do they fit with the OEBPS?
These formats can be created from OEBPS Publications, but they are not themselves OEBPS; they are specific to each particular reading system.
The OEBPS does not specify a way of “boiling down” all the components of an eBook (text, images, stylesheets, etc.) into a single file for download onto a device, nor does it specify how the resulting file is to be protected from piracy. Each reading system, therefore, has its own way of handling compression and encryption.
See the section on reading systems for additional discussion.
How do I turn the multiple files of an OEBPS Publication into a single file for download into a reading system?
Compilation and compression of multiple files into a single file is dependent on each individual reading system. Consult the website for the reading system you are interested in to learn how to do this.