There are many types of OPC Versions and Protocols:

• DA – Data Access
• UA – Unified Architecture 
• .NET (formally XI - Express Interface - think Remoting/WCF)
• HDA – Historian Data Access 
• AE - Alarms and Events

MI only supports OPC-DA protocol

The main reason is that OPC-DA is by far the most commonly used standard in the industry. It is also the most mature as it has been around for many years. 

DELMIA Apriso MI has an OPC DA 2.05a certification.