supported by Apache HTTPd's `mod_include`:
http://web.archive.org/web/19971210170837/http://hoohoo.ncsa.uiuc.edu/docs/tutorials/includes.html
- http://httpd.apache.org/docs/current/mod/mod_include.html
+ http://httpd.apache.org/docs/2.2/mod/mod_include.html
ssic uses the `CGI::SSI` Perl module for directive processing.
* `DOCUMENT_URI` is the current filename.
* `LAST_MODIFIED` is the modification date of the current document.
+Flow Control Commands
+---------------------
+
+The flow control commands are:
+
+ <!--#if expr="test_expression" -->
+ <!--#elif expr="test_expression" -->
+ <!--#else -->
+ <!--#endif -->
+
+If `test_expression` evaluates to false, processing of basic commands is
+suspended until the next `elif`, `else`, or `endif` is encountered. If
+`test_expression` evaluates to true, processing of basic commands is
+suspended between any following `elif` or `else` commands and the next
+`endif` command.
+
+`test_expression` is a Perl expression, which is passed to Perl's
+`eval()` function. Variables may be expanded but should be quoted.
+
+The following example will output "foo is bar" if the variable `foo` is
+set to the value "bar":
+
+ <!--#if expr="'$foo' eq 'bar'" -->
+ foo is bar
+ <!--#endif -->
+
+The following example checks the SSI interpreter and uses the correct
+expression syntax for either ssic or `mod_include` from Apache HTTPd 2.2
+or earlier:
+
+ <!--#if expr="'$__SSIC__' eq '__SSIC__'" -->
+ <!-- Apache HTTPd 2.2 mod_include -->
+ <!--#if expr="$foo = 'bar'" -->
+ foo is bar
+ <!--#endif -->
+ <!--#else -->
+ <!-- Server Side Includes Compiler -->
+ <!--#if expr="'$foo' eq 'bar'" -->
+ foo is bar
+ <!--#endif -->
+ <!--#endif -->
+
+This is the recommended way to check the value of the variable
+`__SSIC__`.
+
Copyright Information
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