backoffice dissable view for an existing attribute?

I extended the Media type with two new attributes. One of them should replace the original one (altText). I tried the following Code:

 <context type="Media" component="editor-area" merge-by="type">
     <editorArea:editorArea name="customervalue_editor">
         <editorArea:tab name="hmc.tab.media.metadata">
             <editorArea:section name="hmc.section.media.metadata">
                 <editorArea:attribute qualifier="titleLocalized" />
                 <editorArea:attribute qualifier="altTextLocalized" />
                 <editorArea:attribute qualifier="altText">
                     <editorArea:editor-parameter>
                         <editorArea:name>visible</editorArea:name>
                         <editorArea:value>false</editorArea:value>
                     </editorArea:editor-parameter>
                 </editorArea:attribute>
             </editorArea:section>
         </editorArea:tab>
     </editorArea:editorArea>
 </context>

But the parameter might not exist:

If anyone knows a Wiki-Page where the available parameters are declared, please let me know... Greatings David