1390fe8a_erShell_Scripts_for_SharePoint__Optional__Mandatory
[Example] -RetainObjectIdentity [Description] RetainObjectIdentity ensures the same list GUID and item ID’s are used when migrating a list from one environment to another. It is most commonly used when you have two Web sites that are mirror images of each other, or in a publishing scenario to indicate that a list in one database is the same list in another database. An exception error is raised if you try and use the RetainObjectIdentity property for importing a list that already exists within the same SharePoint Web application. Note: Because databases do not permit duplicate GUIDs, you should be careful when implementing this property. It is only useful in selective migration scenarios [Optional/ Mandatory] 
Optional
M a n d a t o r y
O p t i o n a l
Copy SharePoint lists and document libraries from one site to another using PowerShell | Get-SPScripts : PowerShell Scripts for SharePoint
Optional/ Mandatory