In proportion as we descend the social scale our snobbishness fastens on to mere nothings which are perhaps no more null than the distinctions observed by the aristocracy, but, being more obscure, more peculiar to the individual, take us more by surprise.
Since no date of birth was entered for the patient, his age is null.
We have mentioned above that null anaphora is represented on syntactic trees as “pro”, and that this reflects the native speaker’s intuition that she or he somehow understands what is not overtly expressed and what the content of the null anaphora might be.