Index: openacs-4/packages/xowiki/tcl/form-field-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/xowiki/tcl/form-field-procs.tcl,v
diff -u -r1.282 -r1.283
--- openacs-4/packages/xowiki/tcl/form-field-procs.tcl	18 Jan 2019 12:19:56 -0000	1.282
+++ openacs-4/packages/xowiki/tcl/form-field-procs.tcl	18 Jan 2019 12:30:15 -0000	1.283
@@ -2173,6 +2173,10 @@
         textarea_id: id
       }]
       if {${:allowedContent} ne ""} {
+        #
+        # Syntax rules:
+        # https://ckeditor.com/docs/ckeditor4/latest/guide/dev_allowed_content_rules.html#string-format
+        #
         if {${:allowedContent} in {true false}} {
           append options "  , allowedContent: ${:allowedContent}\n"
         } else {