I note that SharePoint 2010's producer implementation spits out the following in response for allowableActions:
<canAddObjectToFolder>false</canAddObjectToFolder>
<canAddObjectToFolderSpecified>true</canAddObjectToFolderSpecified>
The first term is in the CMIS spec, the second is not, although it is in source code that can be found on the web.
In the case of SharePoint almost every <action> has a <actionSpecified> version.
Not clear if these are extensions or I'm just missing something….
What is the difference?