595. Transporting Between Domains
82:1 We may not transport any object four cubits (about six feet) in a public domain or in a carmelis on Shabbos. It makes no difference whether one carries the item, throws it or passes it. To carry an item in several stages, each less than four cubits, is likewise prohibited.
82:2 We may not carry, throw or pass any object from a private domain to a public domain or a carmelis, nor from a public domain or a carmelis to a private domain, nor from a public domain to a carmelis, nor from a carmelis to a public domain. However, one may take something from a makom patur to a private domain, to a public domain, or to a carmelis, and vice versa, so long as he does not carry the object four cubits in the public domain. Because of the varying opinions as to what constitutes a public domain, a carmelis, and a private domain, a person who is not proficient in these matters must be careful in the absence of an eiruv not to carry any object from where it is resting to a different place unless he is sure it is permitted.