WMF graphics are like scripts for the Windows GDI. A WMF graphic can include vector elements, text, and bitmaps (with up to 24-bit resolution).
The WMF graphic format has limitations:
Bezier curves become polylines
Bezier curves become polylines
WMF does not support Bezier curves. WMF does support ellipses and elliptic arcs, with radii or chords available for the arcs. Bezier curves are represented by polyline segments.
For dashed lines and other non-solid lines, MicroSoft code for WMF images sets line thickness to 1 (one), which is nominally 1.0 twip (1/20 pt) or 0.01 mm. This value is affected by scaling, so you always get the thinnest line drawable. If you try to use a different thickness for a non-solid line, you get the thickness you specified, but the line becomes solid.