You have the software, but not the people who wrote it.

It has been sitting in a bottom drawer for a long time.
Perhaps it used to be in one of your products, perhaps still is in one, but unchanged for years. Perhaps you bought it and never used it. Perhaps you acquired it in some takeover and don't know what it is.

Can you use it as it is now, making a few changes for the current market?
Or do you need to re-write it, using what you have as a design to be implemented using modern tools.
Or re-engineer it, using what you have as a black box whose properties you discover by experiment, providing a specification for something new.
Or do you push it back into the drawer and pretend you have never seen it?

I can scrutinise in depth code I have never seen before and rate its potential for development.

I have evaluated code and documented it for further, successful development.