Configuration Notation
Sizes can be indicated in kilobytes and megabytes:
for example, "8k", "1m".
Unless otherwise specified, size is in bytes.
Time can be indicated in minutes, hours, days and so on:
|M||months, 30 days|
|y||years, 365 days|
For example, "1h 30m", "1y 6M".
Unless otherwise specified, time is in seconds.
 Quoting of Directive Parameters
Parameters to Nginx configuration directives can be quoted by surrounding them with either single or double quote characters. Such quoting makes it possible for parameters to include both whitespace characters and quotes of the other type without having to escape them with a backslash character.
Note Nginx variables are still expanded inside both single- and double-quoted parameters, unless the $ is escaped with a backslash.