This specification defines protocols that have been adopted by X/Open as the means of interoperability between personal computers (PCs) and X/Open-compliant systems. Server Message Block (SMB) is intended for use in situations where X/Open-compliant systems are added to an existing LAN consisting primarily of personal computers. -This specification defines protocols that have been adopted by X/Open as the means of interoperability between personal computers (PCs) and X/Open-compliant systems. Server Message Block (SMB) is intended for use in situations where X/Open-compliant systems are added to an existing LAN consisting primarily of personal computers.