Defines the xsf namespace.
xsd:string
The xmlns attribute is a required attribute of the xDocumentClass element, and is the standard mechanism for declaring XML namespaces.
The following is an example of the xmlns attribute as it is used in the xDocumentClass element:
<xsf:xDocumentClass
xmlns:xsf="http://schemas.microsoft.com/office/infopath/2003/solutionDefinition"
name="urn:microsoft-com:myTravelReport"
author="AuthorName"
description="Travel Report form for entering travel reports, issues, expenses, etc."
dataFormSolution="yes"
solutionVersion = "1.0.0.1"
productVersion="11.0.5106"
solutionFormatVersion="1.0.0.0">
...
</xsf:xDocumentClass>