Plugin settings 

Everything a content element can configure for its plugin, field by field. Which content element offers which field is up to you; Content element example shows a typical set.

Record source 

pages
The storage folders a list reads from. Left empty, the list is not limited to any storage page.
recursive
How many levels below the folders in pages are included.

Both are core fields of the content element, not FlexForm settings.

Target pages and page size 

settings.itemsPerPage
Items per page of a list. Falls back to 20 when nothing usable is set.
settings.page.pid.thuecat_attraction_show
Page carrying the attraction detail content element; list items link there.
settings.page.pid.thuecat_attraction_search
Search result page; search forms on pages without a list submit there.
settings.page.pid.thuecat_trail_show
Page carrying the trail detail content element; trail list items link there.

These are usually set once for the whole site, see Site settings. A content element may override them in its FlexForm.

Picking records 

settings.selectedRecords
Selected lists only: the records to show, in the order the editor picked them. Offer records of the default language; translations are resolved when rendering.
settings.selectedRecord

Detail views only: pins the record the element shows. When set, the URL parameter is ignored, so no link can change what the page renders. Left empty, the record is taken from the URL, which is what links from list items rely on. A pinned record that is hidden or deleted renders the "no data" message instead of falling back to the URL.

Do not pin a record on a page that list items link to as detail page: every link would show the pinned record.

Presets 

A list with a preset becomes a filtered list. A preset restricts the list on every request, and the search-and-filter form on the same page does not show a control for a preset field. It carries the preset values as hidden fields instead. Visitors can narrow the result with the remaining fields, but never widen it, not even with a changed URL.

settings.towns
Records in any of the selected towns.
settings.categories
Records related to any of the selected categories or to a category below them.
settings.keywords
Records related to any of the selected keywords or to a keyword below them, see Keywords.

settings.petsAllowed , settings.isAccessibleForFree , settings.publicAccess Checkboxes. When set, only records marked accordingly are listed.

Several values within one field widen the result; several fields narrow it.

Category and keyword trees 

settings.categories and settings.keywords select sys_category records. Start their tree at the parent category the import writes into, so editors are offered that tree and not every category of the installation:

EXT:myextension/ContentBlocks/ContentElements/attraction-list-filtered/config.yaml
- identifier: 'settings.categories'
  type: 'Select'
  relationship: 'oneToMany'
  renderType: 'selectTree'
  foreign_table: 'sys_category'
  treeConfig:
    parentField: 'parent'
    startingPoints: '###THUECAT_ANCHOR:tx_thuecat_tourist_attraction:category###'
Copied!

The marker reads ###THUECAT_ANCHOR:<table>:<category|keywords>###:

<table>
The record table the content element lists, for example tx_thuecat_tourist_attraction or tx_thuecat_trail .
category or keywords
Which of the two trees.

In the backend form the marker is replaced by the parent category configured for that record kind in the site of the edited content element, see Category and keyword anchors. Where none is configured, the tree starts at the root and offers every category.

Core's ###SITE:…### marker works as well, but reads site settings only and never falls back to the Extension Configuration.

In the search form

The search-and-filter form offers the keyword tree below the keyword parent category, grouped by the keyword sets ThueCat defines. It offers only keywords carried by records the list on the page can return. A site without a keyword parent category offers no keyword choice.

Selecting several keywords widens the result; adding a town or a category narrows it. Selecting a keyword set includes all children below it. The selection survives pagination.

As a preset
settings.keywords restricts a list to the selected keywords, see Presets. The search form then shows no keyword control.
On the detail view
The attraction and trail detail views emit a keywords meta tag built from the record's keywords, joined by ", ". A record without keywords emits none.
Events
Imported events carry keyword relations as well, but no frontend output of this extension reads them.