Hi Ellen,
Welcome to this Microsoft Project newsgroup
Yes it does mean estimate. However, all project tasks are estimates of what
you hope you will achieve. When you over-type the Duration from its default
"1 day?" the ? will disappear indicating that you have made a more positive
statement. You can enter a duration with a ? after it and Project will
treat it as an estimate. Then, you can filter for all estimated durations
so you can see those that need firming up. Quite a useful tool in the pm's
armoury as it gets the plan up and running even if there are some doubtful
areas.
FAQs, companion products and other useful Project information can be seen at
this web address: <
http://www.mvps.org/project/>
Hope this helps - please let us know how you get on

)
Mike Glen
MS Project MVP