UIT stands for Union Internationale de Tir ( International Shooting Union - now ISSF). Walther made several rifles designated ITU because they met the ITU standards for small bore competition. That one was called the ITU BV (Blockverschloss or block closing); the others were bolt action, as was the UIT Special. (The Blue Book is in error in saying that the UIT BV was earlier called the UIT Special - they were different guns.)
That is one fine target rifle. The last MSRP was $1700 and one like new will bring $1300 or so.
Jim