A method and apparatus for characterizing information about design attributes is described. Each component carrier comprises a number of subcarriers spaced apart by a system subcarrier frequency spacing. Additionally, the method includes selecting one parameter pair signal of the plurality of parameter pair signals and generating a measured parameter signal responsive to the selecting. The de-multiplexerpriority circuit determines the data transfer rates for each of the different data streams based on the assigned priority. In some embodiments, this invention pertains to methods for the preparation of isotopically enriched N-substituted piperazine acetic acids.