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

appsforoffice.microsoft.com

This domain is used to reference the production version of the Office.js library.

href="https://appsforoffice.microsoft.com/lib/1/hosted/Office.js" 

This was also used to reference the first version of the Fabric UI Front End Framework components.
These particular components have not been updated since February 2017.

href="https://appsforoffice.microsoft.com/fabric/2.6.1/fabric.min.css" 
href="https://appsforoffice.microsoft.com/fabric/2.6.1/fabric.components.min.css" 

static2.sharepointonline.com

This domain is used to reference files from the Fabric UI Front End Framework.
Any references to "office-ui-fabric-core" are the Office UI Fabric Core components.
These "office-ui-fabric-core" components are still being updated.

href="https://static2.sharepointonline.com/files/fabric/office-ui-fabric-core/9.6.0/css/fabric.min.css" 

Any references to "office-ui-fabric-js" are the Office UI Fabric JavaScript components.
These "office-ui-fabric-js" components have not been updated since February 2017.

href="https://static2.sharepointonline.com/files/fabric/office-ui-fabric-js/1.4.0/css/fabric.min.css"