Some Alfresco features, such as aspects, have no corresponding CMIS definition but are supported in different ways.
In the Alfresco 4.2 Community and Enterprise installations that I have, the getTypeChildren call (that is, http://localhost:8080/alfresco/api/-default-/public/cmis/versions/1.1/atom/types) returns the cmis:secondary type, which means that Alfresco supports this CMIS 1.1 base type. Secondary types are used to apply extra properties to a CMIS object. More than one secondary type can be applied to an object. Alfresco exposes any aspects (basically a group of properties) that have been applied to a node using this type.
To find out what aspects have been applied to an object, we can request the properties for the object and look at the cmis:secondaryObjectTypeIds property. In the following command, we are getting the properties for the /Figure1.png file previously uploaded:
$ curl -u admin:admin "http://localhost:8080/alfresco/api/-default...