OOXML is over 600 pages, yes. With lots of contradictions and filler words btw. And a "standard" (with scandals abound) that has most of the format as proprietary extensions. And MS Office/365 doesn't even keep to it, so other office suites never have as good support of the format as MS itself.

Use ODF to save your documents. MS started their "standard" because of it anyway, fearing losses in their customer base (that bound them to Windows).