>>Hi Dragan,
>>
>>See file #9704 Convert SYS(2015) value back
>
>Ah, so it cycles in 100 years. Dang... what do we do in 2091? There will be repeated values!

I would be very happy to see this problem in 2091!

#DEFINE SYS_2015    '_'+STR(YEAR(DATE()),4)+SYS(2015)

ACTIVATE SCREEN 
? SYS_2015

Clearly the question recurs in '10000!
But perhaps there will be no human being to suffer for this.