If 16.20 is the active TTU, then we would have the following:
/opt/teradata/client/ODBC_32/locale -> /opt/teradata/client/16.20/odbc_32/locale
/opt/teradata/client/ODBC_32/lib -> /opt/teradata/client/16.20/lib
/opt/teradata/client/ODBC_32/include -> /opt/teradata/client/16.20/include
/opt/teradata/client/ODBC_64/locale -> /opt/teradata/client/16.20/odbc_64/locale
/opt/teradata/client/ODBC_64/lib -> /opt/teradata/client/16.20/lib64
/opt/teradata/client/ODBC_64/include -> /opt/teradata/client/16.20/include
Inside odbc.ini and odbcinst.ini, all file paths are given in terms of release independent paths which use the symbolic links given above.
For example, the driver location given in /opt/teradata/client/ODBC_32/odbc.ini is Driver=/opt/teradata/client/ODBC_32/lib/tdataodbc_sbu.so which corresponds to /opt/teradata/client/16.20/lib/tdataodbc_sbu.so if 16.20 is the active TTU.