how to associate a codelist with a field in config-editor.xml

[smrgeoinfo]

I have a number of vocabularies that need to be used for populating various text fields in the DDE metadata profile. We have labels and definitions, I can easily generate skos representations. I have gotten a field with templateModeOnly="true" to and a codelist from codelists.xml defined in the template/values/key/codelist element; this shows existing data, but I need to be able to create an add button in the editor that adds a value limited to the codelist.

I tried

         <action type="add" name=" " btnLabel="Add DDE acquisition type" 
            or="acquisitionInformation"
            in="/mdb:MD_Metadata">
            <template>
              <values>
                <key label="acquisitionCode" 
                  xpath="gco:CharacterString">
                  <codelist name="DDEAcqusitionTypeCode"/>
                </key>
              </values>
              <snippet>

                  <mac:MI_AcquisitionInformation>
                    <mac:operation>
                      <mac:MI_Operation>
                        <mac:description>
                          <gco:CharacterString>{{acquisitionCode}}</gco:CharacterString>
                        </mac:description>
                        <mac:status gco:nilReason="unknown"/>
                      </mac:MI_Operation>
                    </mac:operation>
                  </mac:MI_AcquisitionInformation>
              </snippet>
            </template>
          </action>

this displays teh button, but when you click on it, nothing happens.
in config-editor.xml, batchEdit section, I see:

 <field name="topicCats" xpath="mri:identificationInfo/*/
                      mri:topicCategory" use="data-gn-codelist-picker"
        codelist="mri:MD_TopicCategoryCode" indexField="topicCat" insertMode="gn_create">

and in https://github.com/geonetwork/core-geonetwork/pull/7227

<field xpath="/*/gmd:identificationInfo/*/gmd:resourceConstraints/*[gmd:accessConstraints]/gmd:otherConstraints"
                 del="../.."
                 use="data-gn-keyword-picker">
            <directiveAttributes 
                                 data-thesaurus-key="external.theme.httpinspireeceuropaeumetadatacodelistLimitationsOnPublicAccess-LimitationsOnPublicAccess"
                                 data-display-definition="true"
                                 data-show-hints-on-focus="true"
                                 data-thesaurus-concept-id-attribute="xlinkCOLONhref"/>
          </field>

After some sleuthing around, I found code for keywordPicker (and keywordSelector, but not codelistPicker) in geonetwork\core-geonetwork\web-ui\src\main\resources\catalog\components\thesaurus\ThesaurusDirective.js, but its not clear what the directive attributes in the example from 7227 do. I assume the key links to the skos file in some fashion? how does this work to bind a text box field element to a codelist? Questions

1. does the codelist need to be SKOS (or ISO19135, but I'm not going there...)
2. how is the codelist bound to a field using the keyword picker or selector
3. can a template in an add action bind keys to a codelist. Why isn't my example with acquisitionInformation working?
4. I'd like the values to show up as displayed in the topicCategory control-- is that a different directive? How is that configured?

[fxprunayre]

For add action, you can only have multiple snippet https://docs.geonetwork-opensource.org/4.2/customizing-application/editor-ui/creating-custom-editor/#creating-custom-editor-action but there is no support to suggest snippet from a codelist.

The other option is indeed to use the keywordPicker directive to configure an element to use a thesaurus. See examples https://github.com/geonetwork/core-geonetwork/blob/main/schemas/iso19139/src/main/plugin/iso19139/layout/config-editor.xml#L54-L79

[smrgeoinfo]

Keyword picker worked, sort of..., e.g.

<field name="DDEacquisitionType" xpath="mac:MI_Operation/mac:description"  
            or="description"  in="mac:MI_Operation"
            use="data-gn-keyword-picker"  del="../../../..">
            <directiveAttributes data-thesaurus-key="local.theme.acquisitioncodeskos" />
          </field>

the pick list that is displayed are all labeled "undefined'. If you pick one, it show the term from the vocabulary.