The documentation for ESRI's File Geodatabase API (downloadable from http://www.esri.com/apps/products/download/) says regarding its MultiPartShapeBuffer Class:
These functions provide access to the shape buffer. Consult the extended shapefile format document for the buffer layout.
I found the "ESRI Shapefile Technical Description" here: https://www.esri.com/library/whitepapers/pdfs/shapefile.pdf, but it doesn't describe curves and some of the other geometry that a file geodatabase can contain.
Where can I can I find the "extended shapefile format document" to which they are referring, or another source that contains byte by byte buffer layouts for these additional geometry types?