CDATA标签被注释掉了

Question

我试图在PHP文档中使用CDATA标记，但不幸的是，当它输出时，CDATA标记之间的任何内容都被注释掉了。有谁知道为什么？

                $fields =   'data=<?xml version="1.0" encoding="UTF-8"?>
                        <post>
                            <employer_email>#</employer_email>
                            <employer_password>#</employer_password>
                            <position_title>'.$post_title.'</position_title>
                            <position_ref>'.$postID.'</position_ref>                                
                            <position_region>'.$region1.'</position_region>
                            <position_city>'.$position_city1.'</position_city>
                            <position_industry>'.$job_category1.'</position_industry>
                            <position_job_type>'.$job_type1.'</position_job_type>
                            <position_job_description><![CDATA['.$mm.']]></position_job_description>
                        </post>';


                echo "<pre>";
                print_r ($fields);

然后它输出product_job_description部分，如下所示：

<position_job_description><!--[CDATA[Associate Dentist /Penzance, Cornwall / Full Time.MBR Dental are currently assisting a dental practice located in Penzance, Cornwall to recruit an Associate Dentist to join their team.Full Time opportunity.5000 UDAs.&pound;10 per UDA.Strong Private Potential.45/55 Private Fees .For more information please send your CV to #]]--></position_job_description>