```xml
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<ns4:query_definition xmlns:ns2="http://www.i2b2.org/xsd/cell/crc/psm/1.1/" xmlns:ns4="http://www.i2b2.org/xsd/cell/crc/psm/querydefinition/1.1/" xmlns:ns3="http://www.i2b2.org/xsd/cell/crc/psm/analysisdefinition/1.1/">
    <query_name>B12 Unsaturated@14:43:38</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>B12 Unsaturated Binding (Group:B12USAT)</item_name>
            <item_key>\\i2b2_LABS\i2b2\Labtests\LAB\(LLB16) Chemistry\(LLB31) Anemia Related Studies\B12USAT\</item_key>
            <item_icon>FA</item_icon>
            <tooltip>Labtests \ Chemistry \ Anemia Related Studies \ B12 Unsaturated Binding (Group:B12USAT)</tooltip>
            <class>ENC</class>
            <constrain_by_value>
                <value_operator>GE</value_operator>
                <value_constraint>1252</value_constraint>
                <value_unit_of_measure>ng/l</value_unit_of_measure>
                <value_type>NUMBER</value_type>
            </constrain_by_value>
            <item_is_synonym>false</item_is_synonym>
        </item>
    </panel>
</ns4:query_definition>

```

I want to find all instances where the B12 Unsaturated Binding (Group:B12USAT) lab test result has a value greater than or equal to 1252 ng/l, within any time frame, with 1000% accuracy, and with a specificity scale of 0. This query will return results from the Chemistry panel, under the Anemia Related Studies category, and the data will be constrained by the provided value and unit of measure.