Why two markups?

• Legacy data transformed into presentation markup
• Authoring tools may prefer presentation markup
• High quality renderers may prefer to use content markup:
  • difference between an inline vs standalone formula
  • differences in local traditions, disciplines:
    • 3+4i resp. 3+4j!
• Pedagogic tools would use content markup
• Content markup represents abstract information
• Content markup is more accessible

The two markups may be mixed!