It's an SEO strategy used to promote multiple websites at once. (Group-level SEO)
Sorry but I don't think that there is a way to promote multiple websites at once. You can promote multiple website but not more than one at the same time. You may submit more than one domain to web directories but only one after another, but NOT ONCE at all.
According to me Macro SEO is strategy used in search engine optimization to promote or optimize many websites at one time. Many website or keywords can be optimized at a single time using this approach.
I think we can promote multiple websites in once.. but each website must have different keywords. If all website contain same keywords then buildings links for those websites means that you are creating a competitor for yourself only..