It's from regular Edif, DarkEDIF adds multi-language JSON and JSON object properties (and other stuff it's been so long), not any changes to the Edif struct :3
I based Lacewing Blue Client (e.g. Bluewing)'s code from regular Lacewing Relay Client, which was Edif. The basic idea is you have a "global key", some text identifier, and the way ext data works in Edif is its name -> void * pairs.
By appending in your ext name or something, you exclude any unintended crossovers with other Edif exts, and then you just have to work out if you need to track references.
(I do for Bluewing, as I need to know when to close the connection - e.g. when number of objects using the GlobalInfo hits 0. But since Lacewing Relay isn't multithreaded it's implicitly closed so I don't think it does.)
Your main port of calls are throwing in global key/is-global properties in the edPtr (or in the JSON if you're using DarkEDIF), then reading/writing global data in Extension ctor and dtor. There may be other extensions using that technique in the repository, but I can't recall off-hand.