```xml
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<ns3:query_definition xmlns:ns2="http://www.i2b2.org/xsd/cell/crc/psm/1.1/" xmlns:ns4="http://www.i2b2.org/xsd/cell/crc/psm/analysisdefinition/1.1/" xmlns:ns3="http://www.i2b2.org/xsd/cell/crc/psm/querydefinition/1.1/">
    <query_name>LDH (Group:LDH)@00:43:25</query_name>
    <query_timing>ANY</query_timing>
    <specificity_scale>0</specificity_scale>
    <panel>
        <panel_number>1</panel_number>
        <panel_timing>ANY</panel_timing>
        <panel_accuracy_scale>100</panel_accuracy_scale>
        <invert>0</invert>
        <total_item_occurrences>1</total_item_occurrences>
        <item>
            <hlevel>4</hlevel>
            <item_name>LDH (Group:LDH)</item_name>
            <item_key>\\i2b2_LABS\i2b2\Labtests\LAB\(LLB16) Chemistry\(LLB21) General Chemistries\LDH\</item_key>
            <item_icon>FA</item_icon>
            <tooltip>Labtests \ Chemistry \ General Chemistries \ LDH (Group:LDH)</tooltip>
            <class>ENC</class>
            <constrain_by_value>
                <value_operator>EQ</value_operator>
                <value_constraint>H</value_constraint>
                <value_unit_of_measure>u/l</value_unit_of_measure>
                <value_type>FLAG</value_type>
            </constrain_by_value>
            <item_is_synonym>false</item_is_synonym>
        </item>
    </panel>
</ns3:query_definition>

```

I want to find all instances of the LDH (Group: LDH) lab test within the Chemistry panel, specifically the General Chemistries section, with a value constraint of "H" and a unit of measure of "u/l" (international units per liter), where the timing is anytime and the specificity scale is set to 0, with an accuracy scale of 100 and only one item occurrence per panel. This query is a part of the i2b2 query builder and follows the specified xml format.