Final answer:
Y-Type details' retention period post-MICAP in a supply system varies and depends on organizational policies or system specifics, which are not provided in the question.
Step-by-step explanation:
The Y-Type details for a Mission Capability (MICAP) are maintained in the supply system computer for a specific number of days after MICAP termination. However, without more context or specific reference to a system or protocol, it's not possible to provide an exact number of days.
The information typically varies depending on organizational policies or the specific supply system in use. Organizations often have standard operating procedures detailing the duration such information is retained post-MICAP to ensure they have the necessary historical data for analysis and potential future improvements in the supply chain.