All data kept in belt slots and the scratchpad is annotated with metadata bits. This metadata is initialized on value creation and also doesn’t change over its lifetime. The most important information kept in there is the scalar data width, whether it is a SIMD vector and whether it is a valid value or not. It also carries the floating point state bits of floating point operations and possibly more. This information is used throughout the machine to augment the operations performed on the data, like inferring operand widths, how to handle overflows, how to propagate values resulting from speculative computations etc.