GUID not available in data service model

Question

In SAP CRM you use something called GUID as a unique key to identify entries in a table.
A common scenario is where a user select one entry in table A and get corresponding entries from table B based on the first table selection.
Now I’m trying to build a demo in Visual composer. The problem is that the GUID attribute is never displayed in the data service model after import. In webdynpro the GUID is a BINARY type and in the CRM the type is RAW.
My question is:
Why can’t I see the GUID in the data service model ?

Answer 1

Its a custom one!
Its a very simple fuction module that just shold return a table.
-><b>Function module:</b>     List_files
-><b>Export</b>
   Parameter Name:     ET_DATA
   Associated TYPE:     ZET_FILES_TABLE
   Pass value:     True
-><b>Table type:</b>     ZET_FILES_TABLE
-><b>Line type:</b>     ZET_FILE
Initialization and Access:     Initial Line Number 0
Access:     Standard Table
Key definition:     standard key
Key category:     Non-unique
-><b>ZET_FILE</b>
      -><b>File_GUID</b>
         Component type     GUID     
         Data type: RAW
         Lentgth:     16
         Decimal:     0
-><b>Data element GUID</b> - Globally Unique Identifier
Package:     SOS_MAPPING