Manifest - Schemas

XMLSchema-instance

This is added to the manifest file.
This declares the XML Schema namespace

<OfficeApp xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> 

MailAppVersionOverrides

This is supported in Office.js 1.1 - 2015 September

<VersionOverrides 
    xmlns="http://schemas.microsoft.com/office/mailappversionoverrides/1.1" 
    xsi:type="VersionOverridesV1_1"> 

<VersionOverrides 
    xmlns="http://schemas.microsoft.com/office/mailappversionoverrides" 
    xsi:type="VersionOverridesV1_0"> 

TaskPaneAppVersionOverrides

This is supported in Office.js 1.1 - 2015 September
TaskPaneAppVersionOverridesV1_0.xsd

<VersionOverrides 
    xmlns="http://schemas.microsoft.com/office/taskpaneappversionoverrides" 
    xsi:type="VersionOverridesV1_0"> 

OfficeAppBasicTypes

This is supported in Office.js 1.1 - 2015 September
OfficeAppBasicTypesV10.xsd
This is referenced in the VersionOverrides/Resources element

<OfficeApp xlmns:bt="http://schemas.microsoft.com/office/officeappbasictypes/1.0"> 

XML Schema Dialog

Click on an XML schema file

View > Properties Window
Click on Schemas

Schema Validation

OfficeAppManifestV1_1.xsd - http:/schemas.microsoft.com/office/appforoffice/1.1
offappmanifest-1.1.xsd - http:/schemas.microsoft.com/office/appforoffice/1.1
offappmanifest.xsd - http:/schemas.microsoft.com/office/appforoffice/1.0

Using NuGet

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