There is a difference between Workday XML and Simple XML. Let us understand with a generated report.
Here is the sample report for 3 EEs.
We are selecting 6 fields. Shown below are the field types.
In Simple XML all fields are just fields, it do not differentiate where as in Workday XML notice that the WID's and reference id type show up for each instance related fields ( Single Instance / Multi - Instance).
We can say that, when you run the report and see the related actions on any of the column values, then that is likely to give you WID and reference id type.
<wd:Report_Data xmlns:wd="urn:com.workday.report/pb_Advanced_Report">
<wd:Report_Entry>
<wd:Employee_ID>1234</wd:Employee_ID>
<wd:Worker wd:Descriptor="Aidan Mitzner">
<wd:ID wd:type="WID">12831f1b82954a3a0ad85fb85367</wd:ID>
<wd:ID wd:type="Employee_ID">1234</wd:ID>
</wd:Worker>
<wd:FirstName>Aidan</wd:FirstName>
<wd:Gender wd:Descriptor="Male">
<wd:ID wd:type="WID">d3afbf8074e54970962128e1105a</wd:ID>
<wd:ID wd:type="Gender_Code">Male</wd:ID>
</wd:Gender>
<wd:Marital_Status wd:Descriptor="Single (United States of America)">
<wd:ID wd:type="WID">5e50cb12452487de0caf7f262d4f</wd:ID>
<wd:ID wd:type="Marital_Status_ID">Single_USA</wd:ID>
</wd:Marital_Status>
<wd:Age>48</wd:Age>
</wd:Report_Entry>
<wd:Report_Entry>
<wd:Employee_ID>1235</wd:Employee_ID>
<wd:Worker wd:Descriptor="Wesley Kingston">
<wd:ID wd:type="WID">480fa11010d6501bfc3dad351f1d</wd:ID>
<wd:ID wd:type="Employee_ID">1235</wd:ID>
</wd:Worker>
<wd:FirstName>Wesley</wd:FirstName>
<wd:Gender wd:Descriptor="Male">
<wd:ID wd:type="WID">bf8074e549ffb070962128e1105a</wd:ID>
<wd:ID wd:type="Gender_Code">Male</wd:ID>
</wd:Gender>
<wd:Marital_Status wd:Descriptor="Single (United States of America)">
<wd:ID wd:type="WID">5e50cb12452487de0caf7f262d4f</wd:ID>
<wd:ID wd:type="Marital_Status_ID">Single_USA</wd:ID>
</wd:Marital_Status>
<wd:Age>31</wd:Age>
</wd:Report_Entry>
<wd:Report_Entry>
<wd:Employee_ID>1236</wd:Employee_ID>
<wd:Worker wd:Descriptor="Xaviere Francois">
<wd:ID wd:type="WID">b31600011066de010d5410b714d0</wd:ID>
<wd:ID wd:type="Employee_ID">1236</wd:ID>
</wd:Worker>
<wd:FirstName>Xaviere</wd:FirstName>
<wd:Gender wd:Descriptor="Female">
<wd:ID wd:type="WID">3bec2d0d420283f76f51b928d885</wd:ID>
<wd:ID wd:type="Gender_Code">Female</wd:ID>
</wd:Gender>
<wd:Marital_Status wd:Descriptor="Free Union (France)">
<wd:ID wd:type="WID">f0f5d5eb405b9ffa48755d4d8b41</wd:ID>
<wd:ID wd:type="Marital_Status_ID">Free_Union_France</wd:ID>
<wd:ID wd:type="Marital_Status_Code" wd:parent_type="WID" wd:parent_id="6971ffb4bf0b116fe7651ec789a">UNIFRA</wd:ID>
</wd:Marital_Status>
<wd:Age>42</wd:Age>
</wd:Report_Entry>
</wd:Report_Data>