Macros
    For almost every important task, Zend ships predefined macros that
    are extremely handy. The tables and figures in the following
    sections describe most of the basic functions, structures, and
    macros. The macro definitions can be found mainly in
    zend.h and zend_API.h.
    We suggest that you take a close look at these files after having
    studied this chapter. (Although you can go ahead and read them
    now, not everything will make sense to you yet.)