+ <: unless ($ENV{REMOTE_USER}) { :>
+ You are not logged in.
+ <: } :>
+
+C<< :> >> always stops a code block, even when it is found in a string literal.
+
+=item C<< <:= $expression :> >>
+
+Includes a dynamic expression in your document. The expression is evaluated in
+list context. Please note that the expression should not end a statement: avoid
+semi-colons. No whitespace may be between C<< <: >> and the equal sign.
+
+C<< foo <:= $bar :> $baz >> is like C<< <: print 'foo ', $bar, ' baz'; :> >>.
+
+=item C<< <(filename)> >>
+
+Includes another file before the PLP code is executed. The file is included
+literally, so it shares lexical variables. Because this is a compile-time tag,
+it's fast, but you can't use a variable as the filename. You can create
+recursive includes, so beware! (PLP will catch simple recursion: the maximum
+depth is 128.) Whitespace in the filename is not ignored so C<< <( foo.txt)> >>
+includes the file named C< foo.txt>, including the space in its name. A
+compile-time alternative is include(), which is described in L<PLP::Functions>.
+
+=back
+
+=head2 PLP Functions
+
+These are described in L<PLP::Functions>.
+
+=head2 PLP Variables
+
+=over 22
+
+=item $ENV{PLP_NAME}
+
+The URI of the PLP document, without the query string. (Example: C</foo.plp>)
+
+=item $ENV{PLP_FILENAME}
+
+The filename of the PLP document. (Example: C</var/www/index.plp>)
+
+=item $PLP::VERSION
+
+The version of PLP.
+
+=item $PLP::DEBUG
+
+Controls debugging output, and should be treated as a bitmask. The least
+significant bit (1) controls if run-time error messages are reported to the
+browser, the second bit (2) controls if headers are sent twice, so they get
+displayed in the browser. A value of 3 means both features are enabled. The
+default value is 1.
+
+=item $PLP::ERROR
+
+Contains a reference to the code that is used to report run-time errors. You
+can override this to have it in your own design, and you could even make it
+report errors by e-mail. The sub reference gets two arguments: the error message
+as plain text and the error message with special characters encoded with HTML
+entities.
+
+=item %header, %cookie, %get, %post, %fields
+
+These are described in L<PLP::Fields>.
+
+=back
+
+=head2 (mod_perl only) PerlSetVar configuration directives
+
+=over 22
+
+=item PLPcache
+
+Sets caching B<On>/B<Off>. When caching, PLP saves your script in memory and
+doesn't re-read and re-parse it if it hasn't changed. PLP will use more memory,
+but will also run 50% faster.
+
+B<On> is default, anything that isn't =~ /^off$/i is considered On.
+
+=back
+
+=head2 Things that you should know about
+
+Not only syntax is important, you should also be aware of some other important
+features. Your script runs inside the package C<PLP::Script> and shouldn't
+leave it. This is because when your script ends, all global variables in the
+C<PLP::Script> package are destroyed, which is very important if you run under
+mod_perl (they would retain their values if they weren't explicitly destroyed).
+
+Until your first output, you are printing to a tied filehandle C<PLPOUT>. On
+first output, headers are sent to the browser and C<STDOUT> is selected for
+efficiency. To set headers, you must assign to C<$header{ $header_name}> before
+any output. This means the opening C<< <: >> have to be the first characters in
+your document, without any whitespace in front of them. If you start output and
+try to set headers later, an error message will appear telling you on which
+line your output started. An alternative way of setting headers is using Perl's
+BEGIN blocks. BEGIN blocks are executed as soon as possible, before anything
+else.
+
+Because the interpreter that mod_perl uses never ends, C<END { }> blocks won't
+work properly. You should use C<PLP_END { };> instead. Note that this is a not
+a built-in construct, so it needs proper termination with a semi-colon (as do
+<eval> and <do>).
+
+Under mod_perl, modules are loaded only once. A good modular design can improve
+performance because of this, but you will have to B<reload> the modules
+yourself when there are newer versions.
+
+The special hashes are tied hashes and do not always behave the way you expect,
+especially when mixed with modules that expect normal CGI environments, like
+CGI.pm. Read L<PLP::Fields> for information more about this.
+
+=head1 FAQ and HowTo