"Greg Burkhart" wrote in message
news:FLh_a.132210$YN5.89274@sccrnsc01...

It doesn't seem always true, (frequently ignored?).


Frequently ignored.



CIN to CID is 137.7nm, 6k7 to 0k7 is 66.1nm and FOD to FSD is
127.7nm... Just a few local ones that I looked up quickly.


6K7 and 0K7 are not three-letter identifiers.