```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>Principal Diagn@23:39:45</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>Diabetes mellitus</item_name>
            <item_key>\\i2b2_DIAG\i2b2\Diagnoses\Endocrine disorders (240-259)\Other endocrine gland diseases (250-259)\(250) Diabetes mellitus\</item_key>
            <item_icon>FA</item_icon>
            <tooltip>Diagnoses \ Endocrine disorders \ Other endocrine gland diseases \ Diabetes mellitus</tooltip>
            <class>ENC</class>
            <constrain_by_modifier>
                <modifier_name>Principal Diagnosis</modifier_name>
                <modifier_key>\\i2b2_DIAG\Principal Diagnosis\</modifier_key>
                <applied_path>\i2b2\Diagnoses\Endocrine disorders (240-259)\%</applied_path>
            </constrain_by_modifier>
            <item_is_synonym>false</item_is_synonym>
        </item>
    </panel>
</ns3:query_definition>

```

I want to find all patients with a principal diagnosis of Diabetes mellitus (Endocrine disorders > Other endocrine gland diseases > Diabetes mellitus) within the specified time frame (ANY). The specificity scale is set to 0, meaning that all occurrences of the diagnosis will be considered, and the accuracy scale is set to 100, indicating a high level of confidence in the results. This query will return a single panel with a total of one item occurrence. The class is set to ENC, and the item is not a synonym.