For my own code I will use spdx references in the source code files but still have a LICENSE file in the repo root like I already do with the full text of the l

For my own code I will use spdx references in the source code files but still have a LICENSE file in the repo root like I already do with the full text of the license. IANAL so I can’t say what you legally can and cannot do with other people’s code but I would think that placing a copy of each of the licenses used by others in your repo and name them as LICENSE_THIRDPARTY_MIT, LICENSE_THIRDPARTY_GPL, etc and mention in your README that these correspond to the spdx references found in source files would mean that you were still in compliance. As for the question “does removing lines of not-code make the file smaller or just a little”; it does not reduce the SLOC count of course. Personally I just find the idea of spdx appealing because it means that when I open files to edit them I don’t have to scroll past a lot of license text first. Additionally scanning source files for what license is being used will be simplified.