A simple XML file could have the following layout:
<?xml version="1.0" ?>
<!DOCTYPE ORDER SYSTEM "opi_dtd.dtd">
<ORDER>
<HEADER>
<POH_PROC_TYPE>I</POH_PROC_TYPE>
<PO_NUMBER>OPI-1</PO_NUMBER>
<ORDER_TYPE>PO</ORDER_TYPE>
<CLIENT_PO_NUMBER>OPI-1-C</CLIENT_PO_NUMBER>
<SUP_CODE>A</SUP_CODE>
<ORIGIN>HOME</ORIGIN>
<ISSUED_BY>HOME</ISSUED_BY>
<PO_CURRENCY>USD</PO_CURRENCY>
<PO_RM_CODE>DEFAULT</PO_RM_CODE>
<ORG_ETA_SITE_DATE>23-APR-2001</ORG_ETA_SITE_DATE>
<BUYER>A</BUYER>
<APPROVED_DATE>24-APR-2001</APPROVED_DATE>
<APPROVED_BY>A</APPROVED_BY>
<NLS>
<NLS_PROC_TYPE>I</NLS_PROC_TYPE>
<NLS_ID>1</NLS_ID>
<SHORT_DESC>Short</SHORT_DESC>
<DESCRIPTION>Long</DESCRIPTION>
</NLS>
<LINES>
<POLI_PROC_TYPE>I</POLI_PROC_TYPE>
<POLI_POS>1</POLI_POS>
<POLI_SUB_POS>1</POLI_SUB_POS>
<IDENT_CODE>1</IDENT_CODE>
<POLI_QTY>9</POLI_QTY>
<POLI_QTY_CODE>kg</POLI_QTY_CODE>
<POLI_UNIT_PRICE>3.20</POLI_UNIT_PRICE>
<POLI_CURRENCY>USD</POLI_CURRENCY>
<PRICE_BASE>Q</PRICE_BASE>
<POLI_UNIT_WEIGHT>3</POLI_UNIT_WEIGHT>
<POLI_WEIGHT_CODE>kg</POLI_WEIGHT_CODE>
<POLI_VOLUME>30</POLI_VOLUME>
<POLI_VOL_CODE>m3</POLI_VOL_CODE>
<POLI_DIMENSIONS>10 x 20 x 30</POLI_DIMENSIONS>
<FRT_CODE>CIF</FRT_CODE>
<FREIGHT_VALUE>Site</FREIGHT_VALUE>
<MANUFACTURER>MANUF.</MANUFACTURER>
<PERCENT_US_CONTENT>0</PERCENT_US_CONTENT>
<EXPORT_LICENSE_REQ_IND>Y</EXPORT_LICENSE_REQ_IND>
<EXPORT_LICENSE_NUMBER>LNO</EXPORT_LICENSE_NUMBER>
<SHIPMENTS>
<ISH_PROC_TYPE>I</ISH_PROC_TYPE>
<ITEM_SHIP_POS>2</ITEM_SHIP_POS>
<ITEM_SHIP_SUB_POS>1</ITEM_SHIP_SUB_POS>
<ITEM_SHIP_QTY>9</ITEM_SHIP_QTY>
<DD_CODE>DEFAULT</DD_CODE>
<ITEM_SHIP_RM_CODE>DEFAULT</ITEM_SHIP_RM_CODE>
<ACTUAL_SHIP_DATE>18-MAY-2001</ACTUAL_SHIP_DATE>
<PRED_SHIP_DATE>18-MAY-2001</PRED_SHIP_DATE>
<PROM_INSPECT_DATE>17-MAY-2001</PROM_INSPECT_DATE>
</SHIPMENTS>
<SHIPMENTS>
<ISH_PROC_TYPE>I</ISH_PROC_TYPE>
<ITEM_SHIP_POS>3</ITEM_SHIP_POS>
<ITEM_SHIP_SUB_POS>1</ITEM_SHIP_SUB_POS>
<ITEM_SHIP_QTY>1</ITEM_SHIP_QTY>
<DD_CODE>DEFAULT</DD_CODE>
<ITEM_SHIP_RM_CODE>DEFAULT</ITEM_SHIP_RM_CODE>
<ACTUAL_SHIP_DATE>19-JUN-2001</ACTUAL_SHIP_DATE>
<PRED_SHIP_DATE>19-JUN-2001</PRED_SHIP_DATE>
<PROM_INSPECT_DATE>16-JUN-2001</PROM_INSPECT_DATE>
</SHIPMENTS>
</LINES>
<LINES>
<POLI_PROC_TYPE>I</POLI_PROC_TYPE>
<POLI_POS>2</POLI_POS>
<POLI_SUB_POS>1</POLI_SUB_POS>
<IDENT_CODE>2</IDENT_CODE>
<POLI_QTY>19</POLI_QTY>
<POLI_QTY_CODE>kg</POLI_QTY_CODE>
<POLI_UNIT_PRICE>3.20</POLI_UNIT_PRICE>
<POLI_CURRENCY>USD</POLI_CURRENCY>
<PRICE_BASE>Q</PRICE_BASE>
<POLI_UNIT_WEIGHT>3</POLI_UNIT_WEIGHT>
<POLI_WEIGHT_CODE>kg</POLI_WEIGHT_CODE>
<POLI_VOLUME>30</POLI_VOLUME>
<POLI_VOL_CODE>m3</POLI_VOL_CODE>
<POLI_DIMENSIONS>10 x 20 x 30</POLI_DIMENSIONS>
<FRT_CODE>CIF</FRT_CODE>
<FREIGHT_VALUE>Site</FREIGHT_VALUE>
<PERCENT_US_CONTENT>0</PERCENT_US_CONTENT>
</LINES>
</HEADER>
<HEADER>
<POH_PROC_TYPE>U</POH_PROC_TYPE>
<PO_NUMBER>OPI-2</PO_NUMBER>
<ORDER_TYPE>PO</ORDER_TYPE>
<POINT_OF_ORIGIN>POO</POINT_OF_ORIGIN>
<SUP_CODE>B</SUP_CODE>
<PO_CURRENCY>USD</PO_CURRENCY>
<PO_RM_CODE>DEFAULT</PO_RM_CODE>
<ILV_CODE>IL</ILV_CODE>
<EV_CODE>EV</EV_CODE>
<CCP_CODE>A</CCP_CODE>
<ORG_ETA_SITE_DATE>23-MAY-2001</ORG_ETA_SITE_DATE>
<BUYER>B</BUYER>
<EXPEDITER></EXPEDITER>
<TRAFFIC>C</TRAFFIC>
<LINES>
<POLI_PROC_TYPE>I</POLI_PROC_TYPE>
<POLI_POS>1</POLI_POS>
<POLI_SUB_POS>1</POLI_SUB_POS>
<IDENT_CODE>3</IDENT_CODE>
<POLI_QTY>9</POLI_QTY>
<POLI_QTY_CODE>kg</POLI_QTY_CODE>
<POLI_UNIT_PRICE>3.20</POLI_UNIT_PRICE>
<POLI_CURRENCY>USD</POLI_CURRENCY>
<PRICE_BASE>Q</PRICE_BASE>
<POLI_UNIT_WEIGHT>3</POLI_UNIT_WEIGHT>
<POLI_WEIGHT_CODE>kg</POLI_WEIGHT_CODE>
<POLI_VOLUME>30</POLI_VOLUME>
<POLI_VOL_CODE>m3</POLI_VOL_CODE>
<POLI_DIMENSIONS>10 x 20 x 30</POLI_DIMENSIONS>
<FRT_CODE>CIF</FRT_CODE>
<FREIGHT_VALUE>Site</FREIGHT_VALUE>
<PERCENT_US_CONTENT>0</PERCENT_US_CONTENT>
</LINES>
</HEADER>
</ORDER>