Cooperating with Other Subprocessors

RAA is designed to allow multiple subprocessors to be applied to the data, so it is possible to first apply a burst cut and then some physics selection. However there have to be some ground rules to allow subprocessors to cooperate:-

1. It is better that subprocessors don't reject events during the SAVE mode. For example suppose a subprocessor is only interested in events with an unusual signature. It would be tempting to drop all but possible candidates during input to speed up processing. However, such a filtered data set would cause problems for a burst subprocessor.

2. Subprocessor writers can add words to the summary record, by adding entries to to the RAAR 1 bank but must, of course, avoid name conflicts. Its O.K. for subprocessors to use the same name for the same data word. This may mean that the word's address moves when the subprocessors are used together, but so long as KAA_SUM_WORD_ADDR is used to get addresses this will work.

3. Subprocessors may set, but should not clear, the DISCARD bit of the STATUS word. So once one subprocessor has considered a summary record as discarded, another subprocessor should not reinstate it. This is not to say that processors cannot look at records with a DISCARD bit set. Burst subprocessors need to see all the data, including events that other subprocessors reject.

4. Beyond the DISCARD bit, subprocessors must not set STATUS word bits that they do not own. Ownership will be recorded in raa_com_subp.inc. However the SELECT bit can always be used for temporary selection.