When red and yellow linesmen’s flags were in common use, did one or the other color signify the senior linesman?
USSF answer (May 6, 2008):
Only if the referee said so. Some referees used the red flag for the senior linesman and the yellow for the junior. Some competitions established that as a rule, but it has never been in the Laws as a requirement. The reason for it was simply alphabetical: R comes before Y, ergo R is senior to Y.