MDAC 2.5 SDK - ODBC Programmer's Reference
Appendix D: Data Types
Numeric literals are used when numeric data values are stored in character strings. For conversion of numeric SQL data to an SQL_C_CHAR string, or conversion of numeric C data to an SQL_CHAR or SQL_VARCHAR string, numeric literal syntax is used to specify what is stored in the target. For conversion of a numeric stored as a SQL_C_CHAR string to numeric SQL data, or a numeric stored as a SQL_CHAR string to numeric C data, this syntax is used to validate what is stored in the source.
Numeric literals should conform to the syntax defined in the section "Numeric Literal Syntax" in Appendix C, "SQL Grammar."