RegIEVersion
This variable retrieves the raw Internet Explorer version number, if any. If present, this is the full version number of Internet Explorer on the target system, for example 7.0.5730.11.
Usage
You can refer to this variable as <RegIEVersion>. Do not change its value; it has been carefully configured for cross-platform compatibility and is used internally by the installer. You can use this version number with runtime functions such as $vercmp to test for specific Internet Explorer versions. Alternatively, you can use the VersionIE variable. However, that variable contains a less precise version number.
You can compare version numbers directly using the standard relational operators < <= > >= = and <>, so a conditional expression like RegIEVersion > 7.0 will do a proper version comparison, obviating the need for the $vercmp function.