What is tweed?
It is a multi-shade merle pattern, usually with three or four shades in moderate sized splotches on a pale background. The blue merle version is generally easy to spot. Red merles are sometimes less so. The intermediate colored splotches are generally distributed all over the body. This is not the same as a regular merle with a dilution spot or two. Tweed is caused by the longest of the SINE insertions, Mh.
If harlequin merle Aussies aren’t harlequin, what are they?
Tweed is the name used in the first scientific article to describe this pattern. The author was aware that “harlequin” had been used by some in the breed but gave it a different name specifically to avoid confusion with the Harlequin pattern in Great Danes. His first choice of term, “splotch”, had already been applied to a color occurring in mice.