Web interface Builder (BPS Layouts)

Hi,

I have 3 variables on the web interface layout for BPS.

1) Next fiscal year

2) Planning version

3) Posting level

The user wants to be able to enter multiple values in the posting level variable. Can anyone please help and give me inputs on how can i set the posting level variable so that the user can enter multiple values in it and display the rest of the data on the web layout accordingly.

Thanks

Urmi