hi,
The acquired assets in terms of marriage are the property which are "onerously"(to get in return of something) obtained during this principle of property between the spouses.therefore,the acquisitions before or after this phase(before marriage or after divorce) are not to be deemed as acquired and not subject to seperation.

yet, "during the marriage" , if the participation rule prevails, there is an assumption that any assets obtained are considered as "acquired" property and the one who claims it is not should prove the contrary. (such as it is acquired before marriage or owned gratuitously)