Nested Groups - Calculating Static vs. Nested Membership

Hi,

I can see that others have asked this quistion before, but I can not find any reel answers.

How does iManager calculate which groups are Static and which are Nested?
On the Nested tab I can choose to see either type. But with other tools (like a LDAP-browser) I can see that there is no such information on the objects them selfs.

Please, anyone, tell me how it is done in iManager. Otherwise I will have to do my own (less performance friendly) calculation.

Thank you in advance.

- martin