ap_conf_vector_t seems to be an opaque data type. This is usually used in the old days to define a stable api, which can subsequently change the implementation without changing the api.
ap_conf_vector_t is used only as a parameter for api functions, such as:
- ap_get_module_config
- ap_parse_htaccess
You should not directly manipulate members of this structure. As an OO programming, you can only use the provided functions.