RSI, thank you for the prompt answer to my last question. I have another (and, I'm sure many more will follow). This question could easily have fit without the IDL forum, but I'm putting it here since it is intended for withing the ENVI environment. I'm trying to create a series of tools for analysis and visualization of 'objects'. I have routines for creating and loading 'objects'. I'd like these 'objects' to be persistant so that they don't have to be constantly loaded anytime the user runs a routine using them. I'd like to create something similar to the 'available bands list' for my 'objects'. How can I do this? I tried using a system variable, but those can only be created. They cannot be modified or deleted. Is there another mechanism for having persistant objects within an ENVI session?