Definition - What does Proprietary mean?
For something to be held as being proprietary means that there have been specific ownership rights to an object in question that have formally been granted. A person who has a proprietary interest in something owns the legal rights to that object and can protect those rights in a court of law.
Justipedia explains Proprietary
Proprietary information usually becomes relevant in a legal sense when there is an owner of some proprietary information that is trying to maintain their proprietary ownership of a specific object that they hold dear. For example, if a company has developed a client list through their own work, that client list is proprietary information. If a person or entity has developed a formula for a pharmaceutical drug that has never been invented, that person or entity has a proprietary interest in that formula.