Hi All 
  I am exploring custom document types creation.
I am following Jeff Potts "Alfresco Developer Series - working with Custom content types".
I created "share-config-custom.xml" files, copied "config" element "node-type" from "share-form-config.xml"  did the necessary changes , did changes for "advanced search" in alfresco share, restarted the service
Now from Advanced search, I can see the Custom document types, without adding "config" element of "model-type". 
In the document it says that I have to copy the "model-type" also. 
Now without coping "model-type" I am able to view Custom Document Type Properties in advanced search
Advice requested why I am getting so 
Thanks 
Joseph John