Apple has submitted what might seem like an arcane filing with the Securities and Exchange Commission (SEC) – but the document contains tantalizing details about the computing giant’s interest in blockchain tech.

The document – entitled “Summary of Apple’s Commitment to Responsible Sourcing” – details the company’s commitment “to upholding human rights across its global network of suppliers that support the manufacturing of its mobile communication and media devices, personal computers, and related accessories.” Making note of both its internal work on this front as well as its relations with supply chain providers, the document is largely a description of Apple’s efforts to ethically source materials for its popular products like the iPhone.

Notably, however, the Feb. 15 filing makes mention of Apple’s involvement in the drafting of “Blockchain Guidelines” for the Responsible Business Alliance’s Responsible Minerals Initiative. According to an RBA press release, those “voluntary guidelines” were published in mid-December of last year and “represent a first industry effort to define a common set of principles, attributes and definitions for the application of blockchain technology to support mineral supply chain due diligence.” The press release makes no mention of Apple’s involvement, but the tech firm is listed as a “Company Member” on the effort’s official web page.

The SEC filing also notes that in 2018, Apple chaired the board of the RBA and participated in a number of its internal committees and working groups, including “the blockchain team.”

When iChain?

These details aside, the filing doesn’t touch on what Apple-watchers might most want to know: whether the Cupertino colossus is on the cusp of joining the growing ranks of tech giants that are offering some form of blockchain-related service. Specifically, if Apple is working on some kind of supply chain-focused solution, it hasn’t (yet) shown its cards.

A request for further information about Apple’s work with the RBA was not returned by press time.

As Fortune’s Jeff John Roberts wrote in December, the question of whether Apple will take the proverbial plunge is an active one, with many in the industry contending that “it’s going to take a tech giant like Apple to make blockchain payments work at scale.”

There is demonstrable interest internally, to say the least. The crypto space has seen Apple veterans join industry startups, and in December 2017, as CoinDesk reported at the time, a published patent filing from Apple detailed a proposed program to certify timestamps by combining aspects of blockchain technology with Public Key Infrastructure (PKI).

Apple CEO Tim Cook image credit: John Gress Media Inc / Shutterstock.com