Revaluation of order in transit (ORDTREVAL) postings

Could someone explain under which conditions these postings are created? We have some trouble understanding the mathematics of these postings and I have tried to provoke the system to produce them in a test environment. But so far I have failed.  My test cases are built upon serial tracked parts with Weighted Average, Cost per Part or Cost per Condition, and Distribution Orders between sites in the same company. NB that the same parts and sites have resulted both in INTORDTR transactions with ORDTREVAL postings and without such postings.