Why is LDAP attribute "secretary" called "Superior" in UCS?

There is a standard LDAP attribute called “secretary”, which according to the official specs is intended for:

The ‘secretary’ attribute specifies secretaries and/or administrative assistants, by distinguished name.

But the web UI of UCS labels this “superior”, which I find rather confusing, so before we fill this field with the secretaries of our organization I thought I’d ask here first what the story is on this…?