Searching for Constant container event in binding

Hi All,

I need to pass some extra information into my workflow container. I am looking in Basic Data>Start Events>Binding and in the event container. I cannot find a constant to put into my workflow container &NI_DETAILS&

I have not worked extensively with wf in the past but have never came across this before, normally its very easy to find or it can generate it automatically.

Liam