U3D Export Setting

Universal 3D (U3D) File Format.  The Universal 3D File Format was primarily intended for downstream 3D CAD repurposing and visualization purposes. However it is mostly used in PDF as container for 3D content.

Views

Cameras to Views

Convert Cameras to Views and save them to U3D file. These views will be selectable in views menu.

View page is available in Save As PDF mode.

Miscellaneous

Compression	Use compression built into u3d format. Since U3D in PDF is compressed anyway, there is no big difference in usage of U3D compression.
UV	Write UV coordinates.
Normals	Write normals. Normals may be recreated by PDF reader. You may need to check how model looks in reader without normals. If everything is OK, you may switch this option off.
Materials	Write materials or use default one.
Textures	Write textures or not.
Active Viewport	Save current viewport or not.
Animation	Save animation.
Existing Pivots	Represent pivot points via animation or with help of additional nodes.
Prefix Metadata with Numbers	May be used for keeping order of metadata items in PDF