What does 3 dot means( ... ) in matlab??

I am new in matlab. Can someone please tell me from below code what does that 3 dot ( ... ) means??

defaults = struct(...
'ThresholdDelta', 5*190/255, ...
'RegionAreaRange', [180 1000], ...
'MaxAreaVariation', 0.25,...
'ROI', [1 1 imgSize(2) imgSize(1)]);