What licensing agreement is MS-GIPUSB provided under?

Hi, I'm interested in developing open source bindings/drivers for interacting with GIP controllers on non-Windows OSes (macOS, Linux, etc). MS-GIPUSB is provided as an Open Specification, but I can't find it listed under either of the spec promises, nor the interop promise or the licensing programs found in the Patent and Product Map. My worry is that, by having looked at the API Spec, I've "contaminated" myself and won't be able to, for instance, sell a commercial version of the macOS driver (bundled as part of a larger package, all under the same license) in order to pay for the 100usd/year signing costs Apple requires. More worrying would be such contamination disallowing me from publishing or contributing to such software at all—I'm willing to eat the cost if that's what is required to get better support of these devices on platforms with signing costs like macOS, so if that's the case I'll suck it up and deal with it, but regardless I want to know where things stand here licensing-wise. Thanks!