图书模块如何在分卷的详情里调用自定义字段

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请问各位大佬，图书模块如何在分卷的详情里调用自定义字段？

比如我的自定义字段是 个文本：ceshi

像下面这样写没有效果，不知道为什么？

下面代码来自于 https://www.xunruicms.com/v3doc/2628.html 

想增加模块拓展自定义字段的内容，不知道标签怎么写

 {loop $type $tid $t}

                <div class="row">

                  <div class="col-md-12">

                    <div class="portlet light">

                      <div class="portlet-title">

                        <div class="caption">

                          <h3>{$t.name}<small>{$t.content}</small></h3>

                        </div>

                      </div>

                      <div class="row">

                        {list action=extend field=name,url cid=$id fenjuan=$tid order=id_asc more=1}

                        <div class="col-sm-3">

                          <div class="tile-container">

                            <div class="tile-title text-center">

                              <h5><a target="_blank" href="{$t.lianjie}">{$t.name}{$t.ceshi}</a></h5>

                            </div>

                          </div>

                        </div>

                        {/list}

                      </div>

                    </div>

                  </div>

                </div>

                {/loop}