Hello Jayakumar,
The use of $CMS_REF(#global.ref, abs:1, templateSet: "html")$ creates an absolute link to the current page, depending on the URL creator defined within the generation action of the schedule entry. This could be e.g.
"/en/products/myPage.html"
If a "Prefix for absolute paths" is defined within the generation action of the schedule entry, this is used (before the first "/").
If you get an empty value, you should either get an error or a warning during the generation of the page or it could be caused by the URL creator.
Unfortunately, you haven't provided any context, so I can't give more than this general answer.
Annotation: If an invalid value is used for the templateSet, the attribute is ignored and the link is created for the current templateSet.
Best regards,
Holger