didn't get the answer anywhere else, so please help.
When a prefix is created, its reference is set to 1. And the last deletion/insertion prefix list's reference is incremented
If a prefix list is referred by a routing process like "distribute-list prefix pl1 out", its reference is incremented by 1. The reference counter is a common concept of IOS. It shows how many objects uses the memory block. You can imagine that objects are functions like show commands and data structures like configurations.
Each entry's refcount is more complicated. Some entries refers other entries. This is because prefix-list entries form
a kind of tree data structure and some of entries cannot be deleted without changing links from child entries.
Hits: Preaty straightforward - number of times this prefix-list was called for action - hit.
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