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HTML is good for debugging, but is unsuitable for application use.
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To see the non HTML representation of the XML format, set format=xml.
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<?xml version="1.0"?>
<api>
  <query>
    <allmessages>
      <message name="ipb-blockingself" xml:space="preserve">You are about to block yourself! Are you sure you want to do that?</message>
      <message name="ipb-blocklist" xml:space="preserve">View existing blocks</message>
      <message name="ipb-blocklist-contribs" xml:space="preserve">Contributions for $1</message>
      <message name="ipb-change-block" xml:space="preserve">Re-block the user with these settings</message>
      <message name="ipb-confirm" xml:space="preserve">Confirm block</message>
      <message name="ipb-confirmaction" xml:space="preserve">If you are sure you really want to do it, please check the &quot;{{int:ipb-confirm}}&quot; field at the bottom.</message>
      <message name="ipb-confirmhideuser" xml:space="preserve">You are about to block a user with &quot;hide user&quot; enabled. This will suppress the user&#039;s name in all lists and log entries. Are you sure you want to do that?</message>
      <message name="ipb-default-expiry" xml:space="preserve" />
      <message name="ipb-disableusertalk" xml:space="preserve">Prevent this user from editing their own talk page while blocked</message>
      <message name="ipb-edit-dropdown" xml:space="preserve">Edit block reasons</message>
      <message name="ipb-hardblock" xml:space="preserve">Prevent logged-in users from editing from this IP address</message>
      <message name="ipb-needreblock" xml:space="preserve">$1 is already blocked. Do you want to change the settings?</message>
      <message name="ipb-otherblocks-header" xml:space="preserve">Other {{PLURAL:$1|block|blocks}}</message>
      <message name="ipb-unblock" xml:space="preserve">Unblock a username or IP address</message>
      <message name="ipb-unblock-addr" xml:space="preserve">Unblock $1</message>
    </allmessages>
  </query>
</api>