Slide number decimals

Hi,

I'm wondering if there is a way to get presenter to display the slide number in the outline as decimals when they are set to a lower level in the slide properties. 

For example

Topic 1 (slide level 1)

Topic 2 (slide level 1)

      Topic 2.1 (slide level 2)

I know this can probably be accomplshed in the title manually but I'm wondering if there is a way to force Articulate/Powerpoint to do it automatically?

Thanks

Tom