There are many version os "open" - that is an overloaded word that means different things to different people - what do you understand by the term?
Some other questions - you say that the person you are looking for needs to be single - do you have a preferred age range? You don't give any idea of your own ages. If the lady has a child from other relationships, is that ok? Do you have any pet preferences?
The more information you give, the better the chance of finding folks that stand a chance of fitting your needs and you not wasting your time on folks that are non-starters?
An analogy I have used before is the idea that if company were to put an ad in the paper saying "Looking for workers, send email to firstname.lastname@example.org
" then they may get bombarded with folks that just don't fit what they are looking for, or nobody will apply because they need more information.