#define XML_RPC_EMPTY_STR   ""

XML-RPC protocol have a design that do not allow to send NULL values or "none".

Although, several relevant languages such SQL or python allows to configure a "none" value for every type, that is, the absence of any value, inside XML-RPC it is required to provide a value for all members or variables exchanged.

This macro allows to provide an empty string which is used when it is required to send "empty" values (or not significant). The macro is just a simple redifinition of "", but allows to clearly state that the operation is invoking or returning a non-significant value.