Question: In UTRAN Iub interface Node B Application Part (NBAP) signalling, when a receiving node encounters a Protocol Error, which of the following error classes is related to a mistake in the meaning of the data, rather than its format or structure?
Option 1: Transfer Syntax Error - Incorrect formatting of protocol messages
Option 2: Logical Error - Misinterpretation of data meaning despite correct syntax
Option 3: Abstract Syntax Error - Incompatibility with defined abstract message structure
Option 4: Physical Layer Error - Corruption during transmission at the physical layer
Explanation: A Logical Error in NBAP signalling refers to an error where the data's meaning is misinterpreted, even if the syntax (both transfer and abstract) is correct. This distinguishes it from Transfer Syntax Errors (formatting issues) and Abstract Syntax Errors (structural compatibility problems). Logical Errors impact the semantic understanding of the data, affecting how the receiving node processes the information, making Option 2 the correct answer.