Nial uses the nested array model, which arguably is weird, but is also shared by every surviving APL dialect that supports nesting. J's boxed model comes from S

Nial uses the nested array model, which arguably is weird, but is also shared by every surviving APL dialect that supports nesting. J's boxed model comes from SHARP APL, but A+ was the only other language to pick it up and both those have stopped development. https://aplwiki.com/wiki/Array_model https://aplwiki.com/wiki/Array_model And it sounds like you've found it, but Nial does have the RANK transformer, which looks essentially the same as J's rank conjunction " .