the example builds on the fact that the storage structure of the serial object is known

 Storage Default
{
<Data name="serItemState">
<Value name="1">
<Value>Subject</Value>
</Value>
<Value name="2">
<Value>Change</Value>
</Value>
<Value name="3">
<Value>Color</Value>
</Value>
</Data>
<State>serItemState</State>
<StreamLocation>^rcc.IC.serItemS</StreamLocation>

in this case color  is #3 in serial storage  ==>>  $list(%Value,3)

So you need to know the position of FamilyName in  HS.SDA3.Name (e.g.7 ?)

then you can use $list(%value,7) =  'Twain'   as condition

7 is just a guess as I don't have any HS* classes at hands 

Hi @Otto Medin !
HTTP is basically US ASCII 7bit with some "handcrafted" extensions
- somehow "UTF 7.6" 
🤪 focussing on octets
it works for äöü  but NOT for €  (x20AC)  >>> in URL  %u20AC

for details: https://softwareengineering.stackexchange.com/questions/304419/what-encoding-are-the-http-status-and-header-lines

my hint: Try to avoid it in HTTP headers and stick with 7bit ASCII to be on the save side
browsers are less risk for problems but old applications are