Question: I have seen this 

```
eval="[(6, 0, ref('test_security.base_security_access)])]" 

```

and 

```
eval="[(4, [ref('test_security.base_security_access')])]"

```

in OpenERP 7.0 code.

What is the use of *6,0* and *4* in security and is there any other combination like this, please explain me.

Answer: 
Finally I found the answer in ORM write method.

* For a many2many field, a list of tuples is expected.
 Here is the list of tuple that are accepted, with the corresponding semantics ::

```
         (0, 0,  { values })    link to a new record that needs to be created with the given values dictionary
         (1, ID, { values })    update the linked record with id = ID (write *values* on it)
         (2, ID)                remove and delete the linked record with id = ID (calls unlink on ID, that will delete the object completely, and the link to it as well)
         (3, ID)                cut the link to the linked record with id = ID (delete the relationship between the two objects but does not delete the target object itself)
         (4, ID)                link to existing record with id = ID (adds a relationship)
         (5)                    unlink all (like using (3,ID) for all linked records)
         (6, 0, [IDs])          replace the list of linked IDs (like using (5) then (4,ID) for each ID in the list of IDs)

```

Example:
 [(6, 0, [8, 5, 6, 4])] sets the many2many to ids [8, 5, 6, 4]

* For a one2many field, a lits of tuples is expected.
 Here is the list of tuple that are accepted, with the corresponding semantics ::

```
         (0, 0,  { values })    link to a new record that needs to be created with the given values dictionary
         (1, ID, { values })    update the linked record with id = ID (write *values* on it)
         (2, ID)                remove and delete the linked record with id = ID (calls unlink on ID, that will delete the object completely, and the link to it as well)

```

Example:
 [(0, 0, {'field\_name':field\_value\_record1, ...}), (0, 0, {'field\_name':field\_value\_record2, ...})]
* For a many2one field, simply use the ID of target record, which must already exist, or `False` to remove the link.
* For a reference field, use a string with the model name, a comma, and the target object id (example: `'product.product, 5'`)
`(4, ID)` means link to existing record with id = ID which will adds a relationship to existing record.

While `(6, 0, [IDs])` means replace the list of linked IDs. First it will unlink/delete existing ids with that record and then link to existing record with each ID in the list of IDs. 

For delete existing ids and link ids, it will delete the relationship between the two objects but does not delete the target object itself with `(6, 0, [IDs])`

For more details, [visit here.](http://odedrabhavesh.blogspot.in/2015/08/one2many-field-in-openerp.html)