Uruguay is located at a longitude that would naturally put it in the UTC−4 time zone, but it actually uses the UTC−3 time zone. Uruguay used to observe daylight saving time (UTC−2) from October till March. On 30 June 2015, the Uruguayan government decided to abolish DST, establishing the UTC−3 timezone all year round, starting on December 2015. The term "UYT" is used in and out of the country to convey specific Uruguay time.
IANA time zone database
In the file zone.tab of the IANA time zone database Uruguay has the following zone:
References
Time in Uruguay Wikipedia(Text) CC BY-SA