Many configurations involve repetition of various channel keywords on all or nearly all channels. Maintaining such a configuration is both tedious and error-prone. To simplify some configurations, you can specify which keywords are defaults for various channels.
For example, the following line in a configuration file indicates that all channel blocks following the line will inherit the keywords specified in the line:
defaults keyword1 keyword2 keyword3 ...
The defaults line can be thought of as a special channel block that changes the keyword defaults without actually specifying a channel. The defaults line also does not require any additional lines of channel block information (if any are specified they will be ignored).
There is no limit on the number of defaults lines that can be specified—the effects of multiple defaults lines are cumulative with the most recently encountered (reading from top to bottom) line having precedence.
It may be useful to unconditionally eliminate the effects of any defaults lines starting at some point in the configuration file (at the start of a standalone section of channel blocks in an external file, for example). The nodefaults line is provided for this purpose. For example, inserting the following line in the configuration file nullifies all settings established by any previous defaults channel and returns the configuration to the state that would apply if no defaults had been specified:
Like regular channel blocks, a blank line must separate each defaults or nodefaults channel block from other channel blocks. The defaults and nodefaults channel blocks are the only channel blocks which may appear before the local channel in the configuration file. However, like any other channel block, they must appear after the last rewrite rule.