Read this: The judges continue in paragraph 12, "The determination of when the targeted part is substantial enough to meet this requirement may involve a number of considerations. The numeric size of the targeted part of the group is the necessary and important starting point, though not in all cases the ending point of the inquiry. The number of individuals targeted should be evaluated not only in absolute terms, but also in relation to the overall size of the entire group. In addition to the numeric size of the targeted portion, its prominence within the group can be a useful consideration. If a specific part of the group is emblematic of the overall group, or is essential to its survival, that may support a finding that the part qualifies as substantial within the meaning of Article 4 [of the Tribunal's Statute]."

Several considerations were involved in meeting the requirement to determine what?  
What is the answer? (If it cannot be answered, return "unanswerable")
when the targeted part is substantial enough