Record types 

<?php

use MyVendor\MyExtension\Backend\CommentLabel;

return [
  'ctrl' => [
    'title' => 'my_extension.db:comment',
    'label' => 'name',
    'label_userFunc' => CommentLabel::class . '->getLabel',
    'default_sortby' => 'crdate DESC',
    'hideTable' => true,
    'adminOnly' => true,
    'crdate' => 'crdate',
    'delete' => 'deleted',
    'enablecolumns' => [
      'disabled' => 'hidden',
    ],
    'versioningWS' => true,
    'iconfile' => 'EXT:my_extension/Resources/Public/Icons/Comment.svg',
  ],
  'columns' => [
    'name' => [
      'label' => 'my_extension.db:comment.name',
      'config' => [
        'type' => 'input',
        'required' => true,
      ],
    ],
  ],
  'types' => [
    '0' => [
      'showitem' => 'name, hidden',
    ],
  ],
];

<?php

return [
  'ctrl' => [
    'title' => 'my_extension.db:conference',
    'label' => 'title',
    'descriptionColumn' => 'internal_notes',
    'default_sortby' => 'conference_date DESC',
    'tstamp' => 'tstamp',
    'crdate' => 'crdate',
    'delete' => 'deleted',
    'editlock' => 'editlock',
    'enablecolumns' => [
      'disabled' => 'hidden',
      'starttime' => 'starttime',
      'endtime' => 'endtime',
      'fe_group' => 'fe_group',
    ],
    'languageField' => 'sys_language_uid',
    'transOrigPointerField' => 'l10n_parent',
    'transOrigDiffSourceField' => 'l10n_diffsource',
    'translationSource' => 'l10n_source',
    'versioningWS' => true,
    'origUid' => 't3_origuid',
    'iconfile' => 'EXT:my_extension/Resources/Public/Icons/Conference.svg',
    'security' => [
      'ignorePageTypeRestriction' => true,
    ],
  ],
  'columns' => [
    'title' => [
      'label' => 'my_extension.db:conference.title',
      'config' => [
        'type' => 'input',
        'required' => true,
        'max' => 255,
        'eval' => 'trim',
      ],
    ],
    'conference_date' => [
      'label' => 'my_extension.db:conference.conference_date',
      'config' => [
        'type' => 'datetime',
        'format' => 'date',
        'required' => true,
      ],
    ],
    'internal_notes' => [
      'label' => 'my_extension.db:conference.internal_notes',
      'config' => [
        'type' => 'text',
        'rows' => 3,
      ],
    ],
  ],
  // The fields of the other tabs are added in Configuration/TCA/Overrides/
  'types' => [
    '0' => [
      'showitem' => '
        title, conference_date,
        --div--;my_extension.db:tab.program,
        --div--;my_extension.db:tab.details,
        --div--;core.form.tabs:categories,
        --div--;core.form.tabs:access,
          hidden, --palette--;;access, fe_group, editlock,
        --div--;core.form.tabs:language,
          --palette--;;language,
        --div--;my_extension.db:tab.comments,
        --div--;core.form.tabs:notes,
          internal_notes,
      ',
    ],
  ],
  'palettes' => [
    'access' => [
      'label' => 'core.form.palettes:access',
      // The labels of the fields tell the editors what the dates are for
      'showitem' => '
        starttime;my_extension.db:conference.starttime,
        endtime;my_extension.db:conference.endtime,
      ',
    ],
    'language' => [
      'showitem' => 'sys_language_uid, l10n_parent',
    ],
  ],
];

<?php

use TYPO3\CMS\Core\Utility\ExtensionManagementUtility;

defined('TYPO3') or die();

ExtensionManagementUtility::addTCAcolumns('tx_myextension_talk', [
  'speaker' => [
    'label' => 'my_extension.db:talk.speaker',
    'config' => [
      'type' => 'group',
      'allowed' => 'tx_myextension_speaker',
      'maxitems' => 1,
      'relationship' => 'manyToOne',
      // The speakers are stored in the same folder as the talks
      'elementBrowserEntryPoints' => [
        'tx_myextension_speaker' => '###CURRENT_PID###',
      ],
      'fieldControl' => [
        'editPopup' => [
          'disabled' => false,
        ],
        'addRecord' => [
          'disabled' => false,
        ],
        'listModule' => [
          'disabled' => false,
        ],
      ],
      'behaviour' => [
        'allowLanguageSynchronization' => true,
      ],
    ],
  ],
]);
$GLOBALS['TCA']['tx_myextension_talk']['types']['keynote']['columnsOverrides']['speaker']['config']['minitems'] = 1;
ExtensionManagementUtility::addToAllTCAtypes(
  'tx_myextension_talk',
  'speaker',
  '',
  'after:slug',
);

<?php

use TYPO3\CMS\Core\Utility\ExtensionManagementUtility;
use TYPO3\CMS\Extbase\Utility\ExtensionUtility;

defined('TYPO3') or die();

// A group of its own in the content element wizard and the type select
ExtensionManagementUtility::addTcaSelectItemGroup(
  'tt_content',
  'CType',
  'conference',
  'my_extension.db:tt_content.group.conference',
  'after:plugins',
);

ExtensionUtility::registerPlugin(
  'MyExtension',
  'ConferenceList',
  'my_extension.db:plugin.conferencelist.title',
  'my-extension-conference-list',
  'conference',
  'my_extension.db:plugin.conferencelist.description',
  'FILE:EXT:my_extension/Configuration/FlexForms/ConferenceList.xml',
);

// The plugin lists the upcoming conferences without further settings, so
// a new plugin is saved at once, with its header hidden
$GLOBALS['TCA']['tt_content']['types']['myextension_conferencelist']['creationOptions'] = [
  'defaultValues' => [
    'header_layout' => '100',
  ],
  'saveAndClose' => true,
];

<?php

use MyVendor\MyExtension\Preview\ConferenceTeaserPreviewRenderer;
use TYPO3\CMS\Core\Utility\ExtensionManagementUtility;

defined('TYPO3') or die();

// The fields of the teaser
ExtensionManagementUtility::addTCAcolumns('tt_content', [
  'tx_myextension_teaser_conference' => [
    'label' => 'my_extension.db:tt_content.tx_myextension_teaser_conference',
    'config' => [
      'type' => 'select',
      'renderType' => 'selectSingle',
      'foreign_table' => 'tx_myextension_conference',
      'foreign_table_where' => 'AND {#tx_myextension_conference}.{#sys_language_uid} IN (-1, 0)',
      'relationship' => 'manyToOne',
    ],
  ],
  'tx_myextension_teaser_link_text' => [
    'label' => 'my_extension.db:tt_content.tx_myextension_teaser_link_text',
    'config' => [
      'type' => 'input',
    ],
  ],
  'tx_myextension_teaser_note' => [
    'label' => 'my_extension.db:tt_content.tx_myextension_teaser_note',
    'config' => [
      'type' => 'input',
    ],
  ],
]);

// Add the content element to the "Type" dropdown, after the call for papers.
// Predefined and own fields on the "General" tab and a tab of its own.
// addRecordType() adds the "Extended" tab at the end.
ExtensionManagementUtility::addRecordType(
  [
    'label' => 'my_extension.db:tt_content.conference_teaser',
    'value' => 'myextension_conferenceteaser',
    'icon' => 'my-extension-conference-list',
    'group' => 'conference',
    'description' => 'my_extension.db:tt_content.conference_teaser.description',
  ],
  '
    --palette--;;headers,
    tx_myextension_teaser_conference,
    --div--;my_extension.db:tab.teaser,
      tx_myextension_teaser_link_text,
  ',
  [
    // The page module shows the teased conference
    'previewRenderer' => ConferenceTeaserPreviewRenderer::class,
  ],
  'after:myextension_callforpapers',
);

// Added without a position, so the field is shown on the "Extended" tab
ExtensionManagementUtility::addToAllTCAtypes(
  'tt_content',
  'tx_myextension_teaser_note',
  'myextension_conferenceteaser',
);

<?php

declare(strict_types=1);

namespace MyVendor\MyExtension\Preview;

use Symfony\Component\DependencyInjection\Attribute\Autoconfigure;
use TYPO3\CMS\Backend\Preview\PreviewRendererInterface;
use TYPO3\CMS\Backend\Preview\StandardContentPreviewRenderer;
use TYPO3\CMS\Backend\View\BackendLayout\Grid\GridColumnItem;
use TYPO3\CMS\Core\Domain\RecordInterface;

/**
 * Shows the teased conference and the link text of a conference teaser
 * in the page module. The header, the footer and the wrap of the preview
 * stay the same as for the other content elements.
 */
#[Autoconfigure(public: true)]
final readonly class ConferenceTeaserPreviewRenderer implements PreviewRendererInterface
{
  public function __construct(
    private StandardContentPreviewRenderer $standardContentPreviewRenderer,
  ) {}

  public function renderPageModulePreviewHeader(GridColumnItem $item): string
  {
    return $this->standardContentPreviewRenderer->renderPageModulePreviewHeader($item);
  }

  public function renderPageModulePreviewContent(GridColumnItem $item): string
  {
    $record = $item->getRecord();
    $conference = $record->get('tx_myextension_teaser_conference');
    if (!$conference instanceof RecordInterface) {
      return '';
    }
    return sprintf(
      '<p><strong>%s</strong></p><p>%s</p>',
      htmlspecialchars((string)$conference->get('title')),
      htmlspecialchars((string)$record->get('tx_myextension_teaser_link_text')),
    );
  }

  public function renderPageModulePreviewFooter(GridColumnItem $item): string
  {
    return $this->standardContentPreviewRenderer->renderPageModulePreviewFooter($item);
  }

  public function wrapPageModulePreview(string $previewHeader, string $previewContent, GridColumnItem $item): string
  {
    return $this->standardContentPreviewRenderer->wrapPageModulePreview($previewHeader, $previewContent, $item);
  }
}

<?php

use TYPO3\CMS\Core\Utility\ExtensionManagementUtility;
use TYPO3\CMS\Extbase\Utility\ExtensionUtility;

defined('TYPO3') or die();

// A group of its own in the content element wizard and the type select
ExtensionManagementUtility::addTcaSelectItemGroup(
  'tt_content',
  'CType',
  'conference',
  'my_extension.db:tt_content.group.conference',
  'after:plugins',
);

ExtensionUtility::registerPlugin(
  'MyExtension',
  'ConferenceList',
  'my_extension.db:plugin.conferencelist.title',
  'my-extension-conference-list',
  'conference',
  'my_extension.db:plugin.conferencelist.description',
  'FILE:EXT:my_extension/Configuration/FlexForms/ConferenceList.xml',
);

// The plugin lists the upcoming conferences without further settings, so
// a new plugin is saved at once, with its header hidden
$GLOBALS['TCA']['tt_content']['types']['myextension_conferencelist']['creationOptions'] = [
  'defaultValues' => [
    'header_layout' => '100',
  ],
  'saveAndClose' => true,
];