The thorough answer to Roadmap and possible pitfalls for a first-time software author to publish a paper on a Python package? covers the issue nicely, and it's not yet clear if in my case this paper still needs to be published stand-alone. The reason is that the mathematics behind it will be sufficiently described in a supplemental materials document associated with a (hopefully forthcoming) publication in the general fields of advanced materials and surface science.
Now my question is if the supplemental section of a published paper in a well recognized journal will sufficient to use as a citation in subsequent papers e.g. "coefficients were extracted using the same analysis as previously described in X et al." (or something with less awkward cadence) where the bibliographic item will mention the supplemental section to that paper.
Question: Is this a generally acceptable way to do this, or are supplemental materials not considered to be "real" references, either because (perhaps, just guessing) they are not as thoroughly peer-reviewed as the main paper to which they are attached, or don't appear in the print version and so are not considered as accessible, or for reasons I can't yet imagine?