How do I use the name of the world?

I want to make a mod with a procedure, where I save the results in relation to the world. I tried to use the world dependencie that is downright, but but it didn't become a usable variable. I use some plugins, namely arraylist, file-manager, configuration_files, procedures plus and extras 1. I hope someone can help me. I tried to use it without them, but this also didn't work and the same with deleting and reinstalling it. I hope someone can help me.