The multibyte delimiters used to separate name-value pairs.
Delimiters can contain any characters. They are separated from each other in the string by spaces. If a space is used as part of a delimiter, it must be escaped using a backslash (\). The maximum length of any delimiter is 10, and the maximum size of this parameter is 32.
This parameter is optional and if not specified, the default value is & (ampersand).