I can't answer the original post, but I can tell you that the red stripe in my school represents the "master instructor" rank which technically is a seperate distinction from 4th degree. In practice they do go hand in hand as that the master instructor requirements shadow 4th degree ones so closely.
When I received my 4th degree black belt in 2001 I did not receive this distinction as that my Grandmaster (Soke Michael Kinney) was at that time waiting until 5th degree. I received the title of "Master Instructor" once I received my 5th degree.
That has since changed (I think mostly to more closely allign the school with what others in our assocation were doing) and 4th degree has become the master instructor rank.
Honestly, I rarely wear my belt with the red stripe through it as I consider it a bit fancy really. I save it for special occasions (exams, seminars ect). When teaching or training I generally just wear my black belt with the 5 bars indicating degree.