The CRd field and the N bit contain information for the coprocessor which may be interpreted in different
ways by different coprocessors, but by convention CRd is the register to be transferred (or the first register
where more than one is to be transferred), and the N bit is used to choose one of two transfer length options.
For instance N=0 could select the transfer of a single register, and N=1 could select the transfer of all the
registers for context switching.