The #4S is a new one to me. Must be a new code digit recently adopted by QD.
But I know for a fact that the major labs like QD, Kroll, Labcorp, Concentra, etc; wouldnt use the test inventory code to signify whether a test will be observed or monitored.

Since youre taking an employment-related U/A, you dont have anything to worry about. Employment-related tests are not observed unless you had been suspected of tampering.

So if you were to get caught bringing in any type of "cheating contraband", or if you had submitted a urine sample thats outside the proper temperature range, or exhibited any behavior that would indicate intent to tamper, those would be sufficient cause for a sample collection under direct observation.