PHP common data gateway sets and gets values of common data structures. It provides static functions which can be called from anywhere to set up a common data structure with a name and values for named properties. A data structure is created if one does not exist with the given name. Properties may be changed to a given value specifying a string with the name of the data structure followed by the name of the property, separated by a dot. If no value is passed, the current value of the property is returned.