What's the meaning of "[]", "<>", "{}" in SYNOPSIS of a command?

Question

Here are some examples:

from man page of a command:

$ man man
man [-acdfFhkKtwW] [--path] [-m system] [-p string] [-C config_file] [-M pathlist] [-P pager] [-S section_list] [section] name ...
...

from http://vim.wikia.com/wiki/Power_of_g:

:[range]g/<pattern>/cmd

from http://bullium.com/support/vim.html:

:wq {file}

1. What's the meaning of [...], <...>, {...}, and those things without any surroundings?
2. Is there a standardized definition of the usage of symbols?

Answer 1

The examples you gave vary because the vim commands are to be used within Vim itself, not on the shell command line.

[] is usually reserved for optional arguments on shell commands.

<> in your example is used for required arguments to a vim commmand. {} in your example is used for an optional argument on a vim command.

The later two seem to be VIM specific, but [] is pretty standard notation for signifying optional arguments.