In the maintenance mode, how to detect if feature is already installed?

[mayurbirari]

I would like to know whether the feature was already installed in the first install or not. I know that installshield automatically selects the features in the maintenance mode that were already installed. But I would like to know that in the installscript. Is there any function to do this?
I am using pure installscript project.

[ramraja_55]

You can use FeatureIsItemSelected or FeatureGetData refer to help for implimentation.