hypothesis:
[1] All physical objects and events can have a digital representation of them that allows a digital system to interact with them in a logical fashion.
i.e. Everything from a $1 million mining truck to a melody can be mimicked to some degree by a set of data values and executable rules that will allow their behaviour and existence to be known and manipulated by a digital system. In fact the mining truck probably did not start its real existence beyond an idea in somebody's head ("Boy this dirt is heavy - isn't there a better way to move it?") - until somebody began to define it in a Compute Aided Design file. The tune whistled in a hallway disappears immediately if not recorded by something - as anyone who tries to recreate that really cool melody they had going in their head before the phone rang can attest.
[1a] The reverse is not true.
Most digital objects do not have physical equivalents - poor things.
[1b] The two are not connected - usually.
The digital object that represents the mining truck has no connection to it without a lot of effort by somebody - and even then it is only temporary.
[2] As far as the digital system is concerned - the physical object or event does not exist without its digital representation.
(even if it's a great big mining truck)
note: This is how $1M mining trucks and sometimes nuclear warheads "disappear"
NOTE:
For most systems these representations are given random names - but some - such as "avatar" have become recognized for what they are - a digital equivalent of a physical object - (usually a person in the "avatar" case.)
For hri07e systems digital representations of physical and many logical systems are collected as "data sheets" and the characteristic data values are shown as key codes. These are mostly static - but in the future - the key codes will be converted to functions which are logical and mathematical digitizations of that characteristic. *Which will be one of many describing an object.)