Like C++ #ifdef, you can generate phrases depending on the presence of a macro. Example:

[? __to_be__ To be or not to be]

Here, the phrase "To be or not to be" will only be generated if the macro symbol __to_be__ has been previously defined. The phrase above will not do anything since we haven't defined __to_be__. Now, let's define the symbol:

[def __to_be__]

[? __to_be__ To be or not to be]

Which results in:

To be or not to be

In quickbook 1.7, you can generate output when a macro isn't defined:

[?! __to_be__ Not to be]