You can customize the means by which an Oracle ATG Web Commerce server determines the encoding type of a specific document by sub-classing the EncodingTyper and overriding the getEncodingType() method. In the following example, this method is passed document paths relative to the document root.

atg.servlet.pagecompile.PageEncodingTyper.java:
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/**
 * Get the encoding to use for the specified path.
 *
 * @return the encoding string, or null if there is no encoding
 * corresponding to the specified path
 */
public String getEncodingType (String pPath)
{
  // Your code here.
}