mongo dot notation ambiguity

I love MongoDB, and a certain little ambiguity occurred to me and I was wondering if anyone had seen this before and possibly would know the answer :-). in mongo, to reach into sub-objects, you use dot notation, for example: ``` db.persons.find({ "address.state" : "CA" }) ``` which is simple enough. How (if it does at all) does mongo deal with the difference between: ``` { "address" { "state" : "CA" } } ``` and ``` { "address.state" : "CA" } ``` since dots are legal in keys as far as i know. Additionally, I believe that this would be a legal doc as well: ``` { "address" { "state" : "A" }, "address.state" : "B" } ``` in which case, I can see this query returning either `"A"` or `"B"`: ``` db.persons.find({}, {"address.state"}) // all docs selecting address.state as result. ``` Similar potential issue can arise I imagine with arrays as well: ``` {"a":["test"]} ``` which could be access with: ``` {"a.0"} ``` and of course ``` {"a" {"0" : "test"} } ``` which would also be access with: ``` {"a.0"} ``` thoughts? experiences? Is the conventional wisdom simply not to do that?