An apparatus is provided, that includes an instruction decoder responsive to an anchored-data processing instruction, to generate one or more control signals. Conversion circuitry is responsive to the one or more control signals to perform a conversion from a data value to an anchored-data select value. The conversion is based on anchor metadata indicative of a given range of significance for the anchored-data select value. Output circuitry is responsive to the one or more control signals, to write the anchored-data select value to a register.