Hi H2FC,
Sedo is not exclusive, so if you're parking or selling here, you can also park or list your domains for sale elsewhere simultaneously while listing and setting your domains for sale with us. Make sure however, not to accept an offer here on Sedo, while also accepting an offer through another forum.
Like BELLC1 said, only when the domain is in our auction are you bound to selling the name through Sedo. Accepting an offer constitutes a legally binding agreement and should be given serious consideration. Once an offer has been accepted the buyer has a legal right they can seek to have enforced in a court of law if the seller does not follow through. Sellers who refuse to complete an accepted transaction risk having their Sedo accounts suspended.
Hope this answers your question! Feel free to PM me with any other issues.
Thanks,
Monica