An include line begins with $INCLUDE, starting in column 1, and is followed by a file name, and, optionally, by a new temporary $ORIGIN to be used while reading this file. This feature is particularly useful for separating different types of data into multiple files. An example would be: $INCLUDE /usr/local/adm/named/data/mail-exchanges
The line would be interpreted as a request to load the file /usr/local/adm/named/data/mail-exchanges. The $INCLUDE command does not cause data to be loaded into a different zone or tree. This is simply a way to allow data for a given primary zone to be organized in separate files. Not even the ``temporary $ORIGIN'' feature described above is sufficient to cause your data to branch out into some other zone -- zone boundaries can only be introduced in the boot file.
A $INCLUDE file must have a name on its first RR. That is, the first character of the first non-comment line must not be a space. The current default name in the parent file does not carry into the $INCLUDE file.