It stands for Get Unspent Transaction Output. It is a feature that has only been implemented in XT, I think that Lighthouse needs nodes that support it, maybe others too. It was never in Core, and Classic is Core + 2MB blocks only. Classic is not based off of XT, instead it is based off of Core.
Excited about the potential of Bitcoin Cash in the beautiful country of Belize.
Developer of the RegisterDocuments.com Document Registration Service (using the Bitcoin Cash blockchain).