Due to the nature of Domains far older then 15+ Years our database isn´t complete. Maybe it would be wise to have a default That a Domain is Registered if the DNA didn´t start with R.
For Example the data i have for denic.de looks as DomainDNA like /L8L7L3L4L7L5C2L7> this would visualize like
So only if the first letter is a P the domain must be registered, at start.