The document specifies a procedure for calculating traps of T-head bolts. This provides standard traps which prevent the bolts from rotating during tightening and prevent incorrect mating.
DIN EN 3202:1996 history
1996DIN EN 3202:1996-03 Aerospace series - Holes and traps for T-head bolts - Design standard; German version EN 3202:1995
1996DIN EN 3202:1996 Aerospace series - Holes and traps for T-head bolts - Design standard; German version EN 3202:1995