Conventions in This Book (CGI Programming with Perl)

0.4. Conventions in This Book

Constant Width: is used for HTTP headers, status codes, MIME content types, directives in configuration files, arrays, operators, variable names (except in examples), and computer output in text.
Italics: is used for filenames, pathnames, newsgroup names, Internet addresses (URLs), email addresses, terms being introduced, commands, options/switches, program names, subroutine names, functions, methods, and hostnames.
ALL CAPS: is used for environment variables, HTML attributes, and HTML tags (within angle brackets <>).