Standard graphical representation for ontologies

Hello,

This is my first email in semantic-web-request mailing list. So I may
introduce myself. I am Carlos Tejo, a member of the Semantic Web
activity line at CTIC Foundation, a non-profit organization, where I
work with a team of research fellows.

And my first question: Is there a standard ("de facto" or "de iure")
graphical representation for ontologies?

Best regards,

Carlos Tejo Alonso
R&D Deparment - CTIC Foundation [Asturias, Spain]
www.fundacionctic.org