<chr_abbr type="frq" class="ss" expan="et" cert="yes">et1</chr_abbr> .xx. <chr_abbr type="frq" class="ss" expan="et" cert="yes">et1</chr_abbr>.xx. <chr_abbr type="frq" class="ss" expan="et" cert="yes">et1</chr_abbr>.xxx. <chr_abbr type="frq" class="ss" expan="et" cert="yes">et1</chr_abbr>.xxx. 