In regards to the context of stored procedure execution, this article contains a contradiction and some confusion.

It is my understanding that statements executed within a SP default to the permissions level of the owner of the SP. If a SP was created as dbo.whatever then all statements executed within that SP would be in the context of dbo, meaning that any objects not owner-qualified would be accessed with dbo context first. IE you will never get a dbo.procedure1 with unqualified object names accessing those objects as user1.object. It will always access them as dbo.object.

The article seems to reiterate exactly this: "objects that are not qualified with owner name and referenced in SELECT, INSERT, UPDATE and DELETE statements will default to the owner of the stored procedure". But then it later says something different when explaining that John.Orders would be truncated when John executes a SP owned by Jane. According to the above explanation it would always truncate Jane.Orders since the table name is not qualified in Jane's SP and Jane owns the SP.

So which way is it really?