The following structure is used by the UF_ROUTE routines which
deal with Routing User Preferences. You must allocate a
UF_ROUTE_user_preference_t structure for each preference you
wish to inquire upon or set. Routing User Preferences may have one
of the following types:
UF_ROUTE_USER_PREF_TYPE_STR Single character string
UF_ROUTE_USER_PREF_TYPE_STR_ARRAY Array of character strings
UF_ROUTE_USER_PREF_TYPE_INT Single integer value
UF_ROUTE_USER_PREF_TYPE_INT_ARRAY Array of integer values
UF_ROUTE_USER_PREF_TYPE_DBL Single real value
UF_ROUTE_USER_PREF_TYPE_DBL_ARRAY Array of real values

For inquiry, you may also specify a type of UF_ROUTE_USER_PREF_TYPE_ANY
which matches a preference of any type.

The key field within the structure is a character string of the name of
the User Preference. The count field is used for the ARRAY types to
specify how many array members there are.

The value for a Routing User Preference is specified in the
appropriate member of the "value" union.

Note that the pointers in the value union when returned by the inquiry
functions are allocated by Routing and must be freed using the
UF_free functions.