OEBPS (really epub1) was open sourced before LIT existed. Epub2 is directly developed from OEBPS, and also open.
And Microsoft orphaned LIT. That was the disaster. It was more similar to the idea (proprietary "compiled" binary file, not just compressed) to KFX. It has no connection to EPUB and didn't properly support all languages anyway. LIT was based off totally proprietary CHM (MS Compiled HTML Help).
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