```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>WHITE BLOOD COU@09:42:52</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>5</hlevel>
            <item_name>WHITE BLOOD COUNT (LOINC:6690-2)</item_name>
            <item_key>\\i2b2_LABS\i2b2\Labtests\LAB\(LLB53) Hematology\(LLB57) Complete Blood Count\WBC\LOINC:6690-2\</item_key>
            <item_icon>LA</item_icon>
            <tooltip>Labtests \ Hematology \ Complete Blood Count \ WBC (Group:WBC) \ White Blood Count (LOINC:6690-2)</tooltip>
            <class>ENC</class>
            <constrain_by_value>
                <value_operator>EQ</value_operator>
                <value_constraint>@</value_constraint>
                <value_type>FLAG</value_type>
            </constrain_by_value>
            <item_is_synonym>false</item_is_synonym>
        </item>
    </panel>
</ns4:query_definition>

```

I want to find all patients who have had a white blood count test (WBC) performed (LOINC:690-2) with any result at any time, using the i2b2 query builder. The specificity scale is set to 0, indicating that all results will be included, and the panel accuracy scale is set to 100, meaning the highest level of accuracy is required. The panel is inverted, meaning that only patients who have had this test performed will be included in the results. There is only one item in the panel, and the class is set to ENC (Encounter), indicating that the test was performed during a patient encounter. The query has a tooltip description of "Lab tests, Hematology, Complete Blood Count, WBC (Group:WBC), White Blood Count (LOINC:690-2)". This query is not a synonym for any other item.