The GELLO Expression Language was started in 2001 and introduced in 2002; in 2005, GELLO was adopted as an international standard by Health Level Seven International and ANSI for a decision support language. GELLO Release 2 was completed and approved by ANSI in June 2010. The GELLO specifications have been developed in coordination with the HL7 Clinical Decision Support TC (CDSTC). As of 2021, the GELLO Implementation Guide DSTU was withdrawn from HL7 Version 3 due to inactivity. However, Release 2 of the standard remains as is, despite a low level of use.