Finding The Subtype Of SQL Values
\ unsigned int sqlite3_value_subtype(sqlite3_value*);\
The sqlite3_value_subtype(V) function returns the subtype for an application-defined SQL function argument V. The subtype information can be used to pass a limited amount of context from one SQL function to another. Use the sqlite3_result_subtype() routine to set the subtype for the return value of an SQL function.
Every application-defined SQL function that invokes this interface should include the SQLITE_SUBTYPE property in the text encoding argument when the function is registered. If the SQLITE_SUBTYPE property is omitted, then sqlite3_value_subtype() might return zero instead of the upstream subtype in some corner cases.