This is a count of hits on the directory File Control Block (FCB) cache, meaning lookups that found the needed directory FCB already cached in memory. An administrator compares this against vmsFileDirFCBAttempt to compute a directory FCB cache hit ratio, which reflects how efficiently directory metadata is being reused from memory. For example, a low hit ratio derived from these two counters would suggest increasing the size of the directory FCB cache to reduce disk lookups.