Consistent worldwide age classification convention needed

[PongPingPom]

The problem currently mostly comes from use of the words veterans & seniors interchangeably
To make matters worse, this is also used now in lieu of the word “Master’s”
To a lesser extent this confusion is same for Juniors & Youth as also with Juniors & Seniors
Many countries use Senior to imply adults who are not under age say 18 or 21 or whatever
Other countries such as USA use “Senior” to imply Age over 60
The word “veterans” means entirely something else in say USA where it is associated with military service .
I was looking at the US Open Prospectus and it shows as follows
Veteran 40 & Over
Esquire 50 & Over
Legend 60 & Over
Senior 70 & Over
This seems somewhat OK but not quite because the word Master’s is used of late instead of veterans.
The other problem is use of the word “Adult” which has some negative connotations.
So based on that I would go as follows but it can be altered for groups over age 40

Hopes 12 and under
Cadets 14 & Under
Junior 17 & Under
Youth 20 & Under
Prime (21 - 39) Such as event is hardly held though
Any age event (Do not use Adult or Senior)
Masters 40 & over (or 40-49)
Veterans 50 & over (or 50-59)
Legends 60 & over (or 60-69)
Seniors 70 & over (or 70-79)
Esquire 80 & over (or 80-89)

The age limits can be specified slightly differently by 1 year for lower age groups such as Junior 18 & under or Youth 22 & under and so on

[Phankha]

Senior and veterans are definitely most confusing