The module API version is now 19970526. A new phase of request processing is available, to allow modules to process the request headers early on in the request. If this is not done, compiling the module might result in type-mismatch warnings, although it will still work. Directives can now be defined in more than one module as once. This gives other modules the chance to handle the directive.
Directives can now take up to three arguments, and can take optional arguments.
The function called should declare arguments for the maximum number of argument the directive can take. The way that a module reads PUT or POST data has been completely changed. Modules can request that they get the data after it has been 'dechunked', or they can get the raw data. A HTTP response can include headers to indicate to the client that this response should not be cached at all. When this is set, a 304 response will never be generated.