The syntax for this command looks quite complicated, but it is relatively simple once you understand its structure. Flushing is used to remove all entries from the chain.
Clearing is used to zero out one or more accounting entries.
The command given can be shortened to the shortest unique form. The present version provides packet accounting with each firewall entry. If an index value is supplied, it used to place the entry at a specific point in the chain. The search continues with the next chain entry. Each action will be recognized by the shortest unambiguous prefix.