Normally, the contents of parameters are substituted into messages literally; that is, without being changed. But if you want to use nonprintable byte values, such as 00, in your parameters, you must specify them so that they are substituted at run time.
To do this, specify the parameters like this:
%AH%<hex_data>%
where hex_data is a series of pairs of hexadecimal characters. You can separate the pairs using blank characters if you want. At run time, the bytes represented by hex_data replace the sequence %AH%hex_data%.
For example, to use the two characters DE, specify the parameter like this:
%AH%<4445>%