eScript: By far the most popular scripting language for Siebel CRM. Siebel eScript is an implementation of the ECMA-262 standard, which is also the base of the popular JavaScript language. Siebel eScript is supported on all operating systems on which Siebel CRM can be installed. SiebelVB: A derivative of Visual Basic is supported as a Siebel scripting language as well, albeit its importance and adoption by developers have declined over the last decade. VBScript is only supported on Microsoft Windows operating systems. Source: https://subscription.packtpub.com/book/application_development/9781849681865/22/ch22lvl1sec01/introduction-to-siebel-scripting