defining keywords in FM DITA

[FieryPantone]

Outside FM, I've been using simple keydefs in ditamaps and bookmaps, then calling them with <keyword keyref="xnt"/> in topics:

<keydef keys="xnt">
   <topicmeta>
      <keywords>
         <keyword>XENTURION</keyword>
      </keywords>
   </topicmeta>
</keydef>

When I try to process the same files using FM, I get relatively comprehensible messages like
[keyref] file:xag_menuXML.dita:18:45: [DOTJ047I][INFO] Unable to find key definition for key reference "xnt" in root scope.

Question, then: how/where do I set up keydefs in the FM environment?

Thanks in advance for advice and tips.

[FieryPantone]

Latest discoveries:

• in FM, Insert Child > Keydef initially seems promising, but displays a dialogue without fields for "keys" or "keyword"
•  'Insert element' dialogue for keydef
• in a text editor, I can add the required definition by hand

<keydef keys="xnt"><topicmeta><keywords><keyword>XENTURION</keyword></keywords></topicmeta></keydef>

• back in FM, I can then examine the attributes for the keydef: keys is there, but no sign of keyword … but Structure > DITA > Generate DITA-OT output somehow manages to render the keydef correctly in the output.

I'm fairly sure this is not the way I want to have to work.