That’s how I did understand it:
\procedure getValue()
<$action-setfield $tiddler=test $field=value $value={{{ [[$:/accounting.directory]getindex{$:/name}] }}}/>
<$action-setfield $tiddler=test $field=name $value={{$:/name}}/>
<$action-setfield $tiddler=test text=`name: {{!!name}}<br>
value: {{!!value}}`/>
\end
<$select tiddler="$:/name" actions=<<getValue>> default="select a value">
<$list filter='[[$:/accounting.directory]indexes[]sort[title]]'>
<option value=<<currentTiddler>>>
<$text text=<<currentTiddler>>/>
</option>
</$list>
</$select>
var:
[[$:/name]] => {{$:/name}}
And your dictionary should also have an additional index
select a value:
0.028349g Gold Troy : 000.000.000002