Choose Edit > Preferences, then click the WMF symbol. The following preferences panel appears:

You can choose between two file formats during the export process. When write Windows Metafile is selected, data is saved in the standard WMF format for Windows with the extension wmf. If you select write Enhanced Metafile an EMF file is produced with the extension emf. Files in this format are not compatible with WMF files and require 32-bit Windows systems.