Installing IKEA Boholmen sink, experiences

Hello again,

this Boholmen sink measuring 46.6 x 30 cm is supposed to be "suitable for a cabinet carcass of at least 40 cm width." But the 40 cm cabinets are only 36.4 cm wide inside due to the 18 mm wall thickness! Is the Boholmen sink that much smaller, or is the rim that much wider? Or do they mean a base cabinet of 40 cm width and 60 cm depth, into which the basin is installed rotated by 90°?

IKEA Boholmen Sink, p. 14 f :

Thanks! I, idiot, could have come up with that myself, just by looking in the assembly instructions for the [Boholmen sink].