You can determine if you're on the list tab with something like this:
if interactive:
session=service.webclientsession()
onListTab=session.getCurrentApp().onListTab()
Then assuming you are selecting records (IE using the checkbox) you would want to get the selection by using something like:
resultBean=session.getCurrentApp().getResultsBean()
let selectedRecords=resultBean.getSelection()
iterator=selectedRecords.iterator()
while iterator.hasNext():
assetMbo=iterator.next()
# Your logic here to act on the Mbo