Conventions

This book follows a few typographical conventions:

Italics are used to introduce new terms and for emphasis.

Program text, functions, URLs, and other "computer language" are set in a fixed-pitch font—for example, register_shutdown_function() or www.php.net. Placeholders within syntax lines appear in monospace italic ; for example, in the following syntax, the words host and type will be replaced with the hostname or IP address to check, and the type of record for which to check, respectively.

bool checkdnsrr(string host, [string type]) 

Sometimes a syntax line or a line of code contains much more detail than can possibly fit within the margins of a printed book. In those cases, the

symbol appears at the beginning of a line that should not be broken from the previous line, as in the following example:

echo "A socket connection to host $host on port 
 $port was successfully opened." 

This symbol merely indicates that we ran out of room on the page, and we've tried to place these code-continuation arrows as helpfully and unobtrusively as possible.