When running a SilkTest script, you may find Custom Timers called ST_PROJECT_TimerX which are not explicitly defined in the SilkTest script.
 

These timers can be generated if the optional sTimerName parameter of the SilkTest TimerCreate function is ommitted.  In such cases a default name is generated, TimerXX, where TimerXX is auto-incremented, starting with Timer0. 

Such unnamed timers are also generated internally by some functions in SilkTest, this is being considered for change in future versions of SilkTest.