I make this on the past but now the link does not accept variables.
¿Did someting change?
I got the entire URL on a field then I tell the Custom HTML by code to use the value on the field, cause yo cannot use variables on fix URL.
But the Code just send the value empty.
Example:
<a href="{/dataset/URLPDFConvenio}" target="_blank"><b><span style="font-size: 12px;">Document</span></b></a>