Configuration 

$languageMapping = array(

	//"sys_language_uid" and "isolanguagecode" have to be unique in the array $languageMapping!
	sys_language_uid => isolanguagecode,

	//Example
	1 => 'de', //german
	11 => 'en', //english
	21 => 'it', //italian
	31 => 'fr', //french
);

$GLOBALS['TYPO3_CONF_VARS']['EXTENSIONS']['bgm_hreflang']['countryMapping'] = array(

	//"pageid" is the rootpage of a country branch. It has to be unique in the array $countryMapping!
	pageid => array(

		//"isocountrycode" has to be unique in the array $countryMapping!
		'countryCode' => isocountrycode,

		//'$languageMapping + array(0 => isolanguagecode)' can be assigned more than once with the same "isolanguagecode" in the array countryMapping.
		'languageMapping' => $languageMapping + array(0 => isolanguagecode),

		//This optional 'additionalGetParameters' can be assigned to every language of the current country
		'additionalGetParameters' => array(
			//"sys_language_uid" has to be unique in the array $additionalGetParameters!
			sys_language_uid => additionalGetParameters,

			//Example
			1 => '&foo=bar&john=doe', //append &foo=bar&john=doe to the link to sys_language 1 in this country
		),

		//This optional 'domainName' can be assigned, if you would like to prepend a certain domain name before your urls.
		//It overrides an automatically assigned domain from the typolink function.
		'domainName' => 'https://www.domain.tld',

		//This is optional. You need this, if you want the Germany country branch to be used as Austrian country branch, too.
		'additionalCountries' => array(isocountrycode, isocountrycode, ...),
	),

	//Example
	61 => array( //International
		'countryCode' => 'en',
		'languageMapping' => $languageMapping + array(0 => 'en'),
		'additionalGetParameters' => array(
			1 => '&foo=bar&john=doe',
		),
		'domainName' => 'https://www.my-domain.com',
	),
	111 => array( //Germany and Austria
		'countryCode' => 'de',
		'languageMapping' => $languageMapping + array(0 => 'de'),
		'additionalGetParameters' => array(
			0 => '&foo=0',
			1 => '&foo=1',
			31 => '&foo=31',
		),
		'additionalCountries' => array('at'),
		'domainName' => 'https://www.my-domain.de',
	),
	161 => array( //Switzerland
		'countryCode' => 'ch',
		'languageMapping' => $languageMapping + array(0 => 'de'),
		'domainName' => 'https://www.my-domain.it',
	),
	211 => array( //Italy
		'countryCode' => 'it',
		'languageMapping' => $languageMapping + array(0 => 'it'),
	),
);

//If $_GET['L']==0, pages in this tree are rendered with hreflang="x-default", else only the isolanguagecode is used (without the isocountrycode)
$GLOBALS['TYPO3_CONF_VARS']['EXTENSIONS']['bgm_hreflang']['defaultCountryId'] = 61;

//Cache is cleared in frontend for all related pages if no cache entry for the current page has been found.
//Here you can disable this behaviour, if you are sure the new DataHandler backend hook is enough cache clearing.
$GLOBALS['TYPO3_CONF_VARS']['EXTENSIONS']['bgm_hreflang']['feature']['clearCacheInFrontent'] = true;

page.headerData.30 = USER
page.headerData.30 {
	userFunc = BGM\BgmHreflang\Utility\HreflangTags->renderFrontendList
}