[Koha] opac subfields

[Samo Se]

Hi 
for this loop<!-- TMPL_LOOP NAME="MARCAUTHORS" -->        <!-- TMPL_LOOP NAME="MARCAUTHOR_SUBFIELDS_LOOP" --><!-- TMPL_VAR NAME="separator" --><!-- TMPL_VAR NAME="value" --></a><!-- /TMPL_LOOP -->         <!-- TMPL_UNLESS NAME="__last__" -->|        <!-- /TMPL_UNLESS -->        <!-- /TMPL_LOOP -->
it's display all sub-fields of the field and i want it to display value of the subfield (a) at opac
any help?