<chr_abbr type="frq" class="ss" expan="et" cert="yes">et2</chr_abbr> force. <chr_abbr type="frq" class="ss" expan="et" cert="yes">et1</chr_abbr> hardeme<chr_abbr type="reg" class="dc" expan="" cert="no">t-hbar</chr_abbr> li croi<chr_var letter="s" var="long">∫</chr_var>t. 