An "enclave" is a portion of territory or country that is surrounded by another separate territory or country. For example, the Vatican City and San Marino are enclaves surrounded by Italy, and the old "West Berlin" used to be a West German enclave surrounded by East Germany.
An "exclave" is a portion of land or territory that is cut off and separated from the rest of the country by a different country. The largest exclave in the world is called "Alaska" as it is cut off from the contiguous states (NOT "continental states") by Canada.
This geocache is in an enclave mostly surrounded by the "Eisenhower Corridor" as it separates from C Street to the south into two parts known as A and C Streets to the north. The larger-micro or smaller-small cache is hidden with some container mischief™, but it is in a convenient and classic spot. Please protect the cache from muggles and take care to leave it as you found it.