This feature is intended to facilitate secondary analysis when the primary analysis was done using filters. Input selection is determined by taking the logical OR of the currently defined requirements. A requirement is a set of filters and their descriptions which are logically ANDed together to make up the requirement decision. A decision about an individual filter is made by comparing the specified filter and its associated description to the corresponding filter information in the appropriate TAGB bank in each event. (If an Analysis Control filter was used in creating the input file Analysis Control will have made a TAGB bank for it.) Most filters are simple; a name and parameter set number completely specifies them (ie. the author of the filter has used ANPTRG). Others, most notably TRGSEL, require a TAGB mask to be specified (ie. the author of the filter has used ANFTAG).
Care must be taken in specifying the filter names and parameter
sets since there is no way for Analysis Control to check that the name you
typed in was a valid filter used in making the input file. This means that
the person using this feature must know how the input file was produced.
One way is to know the standard production filter names and parameter
sets, another is to dump the TAGB banks from an event on the file since
the names and parameter sets are invariant within a file (the parameter
set number is the first integer after the filter name). Once input
filtering has been enabled by specifing one or more requirements the
presence of a nonexistent filter will cause that requirement to fail
for every event. If this is the only requirement specified, none of
the input file events will be processed.
The basic command for setting up a requirement is:
INPUT SELECT EVENT/FILTER=MYFILTER
A complete description of this and related commands is in apendix A.