... Events can be selected based on a flexible set of user-specified criteria that allows column values to be compared with numeric values, header parameters, functions, or other column values. To do this, we use a technique in which a filter specification is converted into a tiny C program, which is compiled and linked automatically so that events can be fed to this program and filter results returned to the calling program. ... short PHA . ... select events whose pha value is exactly 10 . ...