do you mean micro? If yes you check below about small scale and large scale management, the only thing I can add is that I've heard that you can't mix models made with those three scale types (small, normal, large)
"After addressing the small scale management needs of the micro-electro-mechanical systems industry in V5.18, CATIA V5.19 delivers large scale management (from 0.1 mm up to 10 kms) capabilities using mechanical infrastructure. This infrastructure enables the user to design large scale 3D objects, such as dams, and to benefit from complete integration in the Generative Drafting and 2D Layout products."
willwang, please check your data, I could be wrong but I don't think macrometer is a length unit. In my book macro is a general prefix meaning large and a macrometer is tool to measure large distances