Which code in code_string symbol for DV_ORDINAL?

[Moretti Leonardo]

I'm wondering how to set code_string value for a DV_ORDINAL.

Having a DV_ORDINAL a structure like this:
<items archetype_node_id="at0004.1" xsi:type="ELEMENT">
<name>
<value>Element name</value>
</name>
<value xsi:type="DV_ORDINAL">
<value>5</value>
<symbol>
<value>Description 5</value>
<defining_code>
<terminology_id>
<value>local</value>
</terminology_id>
<code_string>???</code_string>
</defining_code>
</symbol>
</value>
</items>

which information should I use in code_string of DV_ORDINAL element? The 
integer value or the atxxxx 
code?

For example, if I defined an ordinal element as
ELEMENT[at0004.1] occurrences matches {0..1} matches {    -- Igiene Personale
     value matches {
         5|[local::at0.15],     -- Description 5
         4|[local::at0.14],     -- Description 4
         3|[local::at0.13],     -- Description 3
         2|[local::at0.12],     -- Description 2
         1|[local::at0.11]     -- Description 1
     }
}

has code_string to be set with at0.1x codes or with integer  values (1, 2, 3, 
4, 5)?

Thanks for your help!
Regards

leo