I first saw this on https://pagure.io/releng-automation where they are using this, and I think it's a neat idea.

SPDX is a spec for machine-readable open source license metadata. One feature of the spec is the SPDX-License-Identifier tag which you can put in source file headers, in addition to (or in place of) the traditional pile of verbiage.

https://spdx.org/spdx-specification-21-web-version#h.twlc0ztnng3b

We already have a hacked-up abbreviated form of the GPL verbiage in our headers, because I find the official version too wordy and irritating -- but we could reduce it even further by using this SPDX-License-Identifier tag instead.