Ever since Internet Explorer 5 (IE5), Microsoft has included browser support for "downlevel conditional comments," a non-scripted method of browser detection. Downlevel conditional comments (DCC) are a useful tool for targeting directives to specific versions of Internet Explorer. Downlevel conditional comments consist of an opening statement and a closing statement. Taken together, the statements enclose markup, CSS, JavaScript, or any other element typically included within an (X)HTML document. The DCC may be placed anywhere within the document and executes its contents only for the version(s) of IE specified. This technique is useful for delivering IE-specific stylesheets exclusively to specific versions of IE. Unfortunately, the last line of a DCC may invoke validation errors, but fortunately, there is a fix. This article describes the code and techniques used when including downlevel conditional comments in web documents.

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