The content pages and include areas that may be loaded by a user in the visual editor must not contain PHP code inclusions. All the executable code should reside in the components because this not just makes loading web pages in the editor straightforward but also reduces maintenance cost.

Verify that all the content pages and include areas that may be loaded in the visual editor does not contain PHP code (except for the system prologue and epilogue code).

- For example, instead of:
  <?
  some user defined PHP code
  ?>
  use components:
  <?
  $APPLICATION->IncludeComponent(…);
  $APPLICATION->IncludeComponent(…);
  …
  ?>