This read-write Integer32 sets the 15-minute HEC error level at which a threshold trap should be generated, defaulting to 0, which disables the threshold. This gives an admin the ability to tune HEC-alarm sensitivity separately from the TEI transport-error threshold, since HEC and TEI reflect somewhat different failure modes. For example, after tracing a recurring problem to encryption-related HEC errors, an operator might set stuAtmHecThreshold to a nonzero value specifically to catch recurrences early.