What is the meaning of "#" in ":g/pattern/z#.5"

Question

Like the title, What is the meaning of # in :g/pattern/z#.5.

:g/pattern/z#.5 and :g/pattern/z.5return the same output for me.

In addition, If I want to help description of # with :h command, how to find it?

:h # seems to show another description which is about search.

Answer 1

in this context z.5 and z#.5 are identical. You find the help under :help :#