SHTML
From MobileRead
SHTML is an HTML document (.shtml) that has Server Side Includes (SSI) in the document. These are generally found on Web server documents.
[edit] Overview
The most common use for this is to build a web page that includes several different sources of information. These sources can either be included verbatim or a script may build the inclusion from scratch. SSI capabilities include programmable scripting features sufficient to consider it a programming language in its own right. There are conditional commands and even formatting commands to create a well formed output.