That doesn't work for me. Here's what the detail_in looks like now:
<PDM_MACRO name=dtlStartRow>
<PDM_MACRO name=dtlLookup hdr="Affected Service (c)" attr="affected_service" evt="onBlur='calculateImpact()'" extraURL="KEEP.service_only=1">
<PDM_MACRO name=dtlLookup hdr="Configuration Item (c)" attr=affected_resource extraURL="KEEP.zNoService=1">
And here is the list_in:
<SCRIPT LANGUAGE="JavaScript">
<PDM_MACRO name=sfStart create=false factory=in>
<PDM_IF "$args.KEEP.zNoService" == "1">
document.write('<input type="hidden" name="QBE.NE.class.type" value="Service">');
</PDM_IF>
I even tried adding the following further down after the Affected Service:
<PDM_MACRO name=sfLookup hdr="Configuration Item" attr=affected_resource.name extraURL="KEEP.zNoService=1" factory=nr>