What does it do? The statement tt:cast can be used to assign the content of one reference variable to another reference variable, if the static type of the source variable is more general than the static type of the target variable. This is called a downcast. The statement tt:cast is a special case of the statement tt:assign, in which only reference variables can be declared as source fields and target fields. Reference variables can be declared as follows:
A node node declared in accordance with the addressing rules and to which an ABAP reference variable is bound
A variable or parameter variable defined as a reference variable using tt:ref-type. If downcasting is not successful because the static type of the target variable is less general than the dynamic type of the source variable when the statement runs, the ST program terminates with exception CX_ST_RUNTIME_ERROR.
