According to man ssh_config of openssh, the option format follows.
Empty lines and lines starting with ‘#’ are comments. Otherwise a line is of the format
“keyword arguments”. Configuration options may be separated by whitespace or optional
whitespace and exactly one ‘=’; the latter format is useful to avoid the need to quote
whitespace when specifying configuration options using the ssh, scp, and sftp -o option.
Arguments may optionally be enclosed in double quotes (") in order to represent arguments
containing spaces.
According to
man ssh_configof openssh, the option format follows.