code: public static function toXhtml($strString)
  	{
  		$arrPregReplace = array
  		(
  			'/<(br|hr|img)([^>]*)>/i' => '<$1$2 />', // Close stand-alone tags
  			'/ border="[^"]*"/'       => ''          // Remove deprecated attributes
  		);
  
  		$arrStrReplace = array
  		(
  			'/ />'             => ' />',        // Fix incorrectly closed tags
  			'<b>'              => '<strong>',   // Replace <b> with <strong>
  			'</b>'             => '</strong>',
  			'<i>'              => '<em>',       // Replace <i> with <em>
  			'</i>'             => '</em>',
  			'<u>'              => '<span style="text-decoration:underline">',
  			'</u>'             => '</span>',
  			' target="_self"'  => '',
  			' target="_blank"' => ' onclick="return !window.open(this.href)"'
  		);
  
  		$strString = preg_replace(array_keys($arrPregReplace), $arrPregReplace, $strString);
  		$strString = str_ireplace(array_keys($arrStrReplace), $arrStrReplace, $strString);
  
  		return $strString;
  	}
docs: Convert a string to XHTML
  
  @param string $strString The HTML5 string
  
  @return string The XHTML string