Page Comparison

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You can find the XMLNS for any given form by opening in a number of ways which should all produce the same result.

In the Application Builder

Open your form in the Application Builder and from the hamburger menu choosing choose "Edit Source XML".  From there look for a variable defined on the <data> XML attribute called "xmlns". You do not want one that has "xmlns:jrm", "xmlns:orx" or any other value.

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<?xml version="1.0" encoding="UTF-8" ?>
<h:html xmlns:h="http://www.w3.org/1999/xhtml" xmlns:orx="http://openrosa.org/jr/xforms" xmlns="http://www.w3.org/2002/xforms" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:jr="http://openrosa.org/javarosa" xmlns:vellum="http://commcarehq.org/xforms/vellum">
	<h:head>
		<h:title>New Form</h:title>
		<model>
			<instance>
				<data xmlns:jrm="http://dev.commcarehq.org/jr/xforms" xmlns="http://openrosa.org/formdesigner/3BAC6D49-D1A2-4D41-A39C-DAA034326670" uiVersion="1" version="1" name="New Form">
					<name />
				</data>
			</instance>
		</model>
	</h:head>
</h:html>

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From a Form Submission

From the Submit History report, open any form of the type you are trying to look up. In the "Raw XML" tab, look for the same xmlns attribute on the <data> XML tag of the submission.

In Data Exports

Go to your Data exports page and create a new export using the form you are trying to look up. Then look for the URL parameter called "export_tag" in your browser's URL bar.