Rules for a Standard Processor

• If a processor requires initialisation or termination then routines must be provided for this. Note that there is no need for auto initialisation; the initialisation routine will be called at the appropriate point. The initialisation routine may be recalled if required, if titles change during processing and if the processor supports dynamic titles management.

• A Processor must be able to handle the situation that its inputs (if any) do not exist. Under these circumstances it should issue a warning message and quit. If should not assume the setting of any link apart from LMAST; and it should even check this.

• A processor that produces outputs must be able to handle the situation that its outputs (if any) already exist. 3 responses are possible:-

  Insert

  Do nothing.

  Replace

  Replace outputs.

  Append

  Append additional outputs.

  A MODE parameter passed to the processor determines the required response.

• The processor must support at least one mode; only certain processors will be able to do more. If the processor only supports one mode then it is free to process the MODE parameter in any of the following ways:-
  • Ignore it.

  • Report any error and quit unless it is correct.

  • Use the parameter for some other use e.g. for the filter the mode parameter can indicate the current point in the analysis chain.