Final answer:
The JTIDS/MIDS access mode that allows multiple participants to share common timeslots is called Netted Time Division Multiple Access (NTDMA). It enables efficient bandwidth use and robust communication by ensuring receivers pick up the strongest signal, usually from the nearest transmitter.
Step-by-step explanation:
The JTIDS/MIDS (Joint Tactical Information Distribution System/Multifunctional Information Distribution System) access mode that allows multiple participants to share common timeslots in the same net, leading receivers to pick up the transmission from the closest transmitter, is known as Netted Time Division Multiple Access (NTDMA).
In the NTDMA mode within a JTIDS/MIDS network, users are assigned to timeslots where several users can use the same slot, which is resolved spatially as receivers will 'hear' the strongest signal, usually from the geographically closest transmitter. This process allows for efficient use of available bandwidth and minimizes the risk of collision while ensuring a robust and reliable communication network for military operations.