Apache module: customlog

Apache module mod_log_config
Available ages: en | ja | Ko // now Chinese

Description: logging of the requests made to the server
Status: Base
Module identifier: log_config_module
Source File: mod_log_config.c

Summary
This module provides for flexible logging of client requests. logs are written in a customizable format, and may be written
Directly to a file, or to an external program. Conditional logging is provided so that individual requests may be encoded or
Excluded from the logs based on characteristics of the request.
This module is used to record customer requests. The record can be written into a custom mode, or directly written to a file or an external program. Because conditional records are provided, a single request can be written or filtered based on the characteristics of the request.

Three directives are provided by this module: transferlog to create a log file, logformat to set a custom format, and
Customlog to define a log file and format in one step. The transferlog and customlog directives can be used multiple
Times in each server to cause each request to be logged to multiple files.
This module provides three commands: transferlog is used to create a record file, logformat is used to set the format, and customlog is used to define the record file and record format at a time. The transferlog and customlog commands can be used multiple times in each service to record each request to multiple record files.

... Hold it. After translation, you will know that it is useless to me. If you are interested, go and have a look.
Source: http://httpd.apache.org/docs-2.0/mod/mod_log_config.html#customlog