The key technical contribution of this chapter is in proposing a protocol to detect and identify missing tag events in the presence of unexpected tags. This chapter represents the first effort on addressing this important and practical problem. The key technical depth of this chapter is in the mathematical development of the theory that RUND and RUNI are based upon. The solid theoretical underpinning ensures that the actual reliability of RUND is greater than or equal to the required reliability. We have proposed a technique that our protocol uses to handle large frame sizes to ensure compliance with the C1G2 standard. We have also proposed a method to implicitly estimate the size of the unexpected tag population without requiring an explicit estimation phase. We implemented RUND and RUNI and conducted side-by-side comparisons with four major prior missing tag detection and identification protocols even though none of the existing protocols handle the presence of unexpected tags. Our protocols significantly outperform all prior protocols in terms of actual reliability and detection time.