Tool:Export Subpalette
From ZBrush Info
Whenever a 3D tool is selected, the Tool:Export subpalette becomes visible. It provides options to control how meshes are exported.
Obj: Exports the object in the .obj format and automatically chooses quad polygons.
Dxf: Exports the object in the .dxf format and automatically chooses triangular polygons.
Qud: Sets the object polygons to quads, regardless of the export format.
Tri: Sets the object polygons to triangles, regardless of the export format.
Txr: Includes UV coordinates in exported .obj output.
Flp: Flips the exported texture top to bottom for target applications that require it.
Mrg: Merges points that occupy the same space. Grp: Includes grouping information in the exported output.
Scale: Scales the exported object size. Range = 0.1 to 100. Default = 1
These options apply to all exports. If you've changed them on a previous export, make sure they are still what you want when you do further exports.

