Which form must be attached to classified items requiring special handling?

The correct form to be attached to classified items requiring special handling is the DD 1387-2. This form, known as the Special Handling Tag, is specifically designed for the purpose of indicating that special handling instructions are applicable to the classified items. It communicates necessary information to ensure that the items are managed appropriately throughout their handling and transportation, thereby maintaining security protocols and reducing the risk of unauthorized access.

The other options serve different purposes that do not relate to the special handling of classified items. For instance, the DD Form 214 is a discharge document issued to military service members, primarily used after separation from service. DA Form 31 is a request for leave, which pertains to personnel leave management rather than equipment handling. SF 101 is a form used for purchase requesting and reporting, irrelevant to classified item handling. Thus, the use of the DD 1387-2 is essential for complying with regulations surrounding classified items that necessitate special attention and handling.