<chr_abbr type="frq" class="ss" expan="et" cert="yes">et2</chr_abbr> di<chr_var letter="s" var="long">∫</chr_var>t <chr_abbr type="frq" class="ct" expan="cheualier" cert="no">ch[apost]r</chr_abbr><chr_var letter="s" var="long">∫</chr_var> ent<chr_abbr type="reg" class="dc" expan="ent" cert="no">et-hbar</chr_abbr> ca 