"Delta138" seems to be a keyword or code of some sort, but without context, it's difficult to provide a specific description. It could potentially refer to a flight number, a product model, a project name, or any other identifier depending on the domain it's used in. https://my.sterling.edu/ICS/Academics/LL/LL473__UG11/FA_2011_UNDG-LL473__UG11_-A/Context/Content_Marketing.jnz?portlet=Content_Marketing&screen=Main&screenType=change