Quirks Mode, IE7 Mode, IE8 Mode, and IE9 Mode (All Versions)
String that specifies the HTML Component (HTC) file that contains the tag definition.
This attribute is required when using the IMPORT processing instruction, and must include one of the following values:
#default –an element behavior built into Microsoft Windows Internet Explorer 5.5 or later
#objectID –string that specifies the id attribute of an object tag
The implementation attribute is declared in markup only.