.NET CLR (Common Language Runtime) Within that range, the following subranges have been allocated for different feature areas: 0x10yy for Execution Engine 0x11yy for Metadata, TypeLib Export, and CLDB 0x12yy for MetaData Validator 0x13yy for Debugger and Profiler errors 0x14yy for Security 0x15yy for BCL 0x1600 - 0x161F for Reflection 0x1620 - 0x163F for System.IO 0x1640 - 0x165F for Security 0x1660 - 0x16FF for BCL 0x17yy for shim 0x18yy for IL Verifier 0x19yy for .NET Framework 0x1Ayy for .NET Framework 0x1Byy for MetaData Validator 0x1Cyy for more debugger errors 0x1Dyy for PE Format Validation 0x30yy for VSA errors 1135 errors