There are different ways to do this and it depends a little on how you have setup your model. 

For example, if you are doing a simulation of a set of demand scenarios that you like to explore you could define a set of Scenarios and push the results of a scenario run, say MyResult(i,j), after each run into an output parameter that is indexed over the set of Scenarios, say allMyResults(s,i,j). You can then display the latter parameter in the WebUI. 
 

You can also, instead of adding the index, use the case save functionality and do a compare cases via the Data Manager. This functionality works out of the box and most widget are auto-extended with a case index (not all widgets). This could be a way to compare quickly although it has its limitations with respect to not having access to all individual results when wanting to do actions on the data. Best to explore if this works for you. See also: 

and

https://how-to.aimms.com/Articles/338/338-viewing-schedules-different-scenarios.html

Hi @roy 

Were you able to get your model started with Gertjan’s suggestions?

Hi @Gertjan,

I faced a problem with this solution.

The link you shared it uses CurrentCaseSelection Set. But in the Start this Set is Empty. even if I load a Case (say Case1) as Active or create a new Case(and save it), it does not becoming an element of the set CurrentCaseSelection.   

No, 

It worked partially.

Please see my reply to @Gertjan .

Dear @roy,

The CurrentCaseSelecion functionality is exclusively related to the WebUI data manager functionality.

If you are loading from WinUI or using a CaseFileLoad, it will not populate that set. 

Is that your case? I would suggest the other approaches, as per Gertjan's suggestion.