Customers configuring Apache on the IBM i many times run into problems with Apache directives that do not seem to exist, or that behave in unexpected ways.
Any supported release of IBM i
IBM provides Apache on the IBM i as part of the IBM HTTP Sever Licensed Program.
While IBM HTTP Server is Apache, it is not 100% compatible with Apache as distributed at apache.org. There are some directives that are not supported, and some other directives that are unique to IBM HTTP Server that do some interesting IBM i related things.
When working on IBM HTTP Server, it is better to rely on the manual provided by the IBM online documentation. For example, the online documentation for IBM HTTP Server for V7.3 can be found here:
https://www.ibm.com/support/knowledgecenter/ssw_ibm_i_73/rzaie/rzaiemain.htm
One particularly useful reference is the Directive Finder: