Octopus Mark prefered

Hi,

I'm using Octopus and I would like to know what is the difference between 'Mark prefered (Obj)' and 'Mark Prefered (Gen)'

I can see 'Mark prefered (Gen)' adds a new objective which is an indicator of diversity between the marked solutions and the others (similar toi euclidian distance I guess). It turns a N-objective problem into a (N+1)-objective one, am I right ?

I suppose also that Gen refers to the genotypic space and that Obj to the objective space, but I'm not familiar enough with these notions to guess how it impacts the diversity in the Pareto Front.

So my question is how do these two instructions differ and what are the consequences in terms and diversity, calculation time ... if we choose one or the other or both of them?

And I suppose 'Mark' is just a visual point of reference that has no influence on the search process ?

Thanks in advance !

best,

Gaetan