If the node is blacklisted from being mutated. This is for example when the node covers a C macro.
If the node should not be part of mutant schemata because it is highly likely to introduce compilation errors. It is for example likely when operators are overloaded.
Block nodes that have a high probability of failing from being coverage instrumented.
Multiple branches are contained in the bundle that can be e.g. deleted.
This can, in C/C++, be either a whole if-statement or switch.