For compatibility between product versions, the library OLDNAMES.LIB maps old names to new names. For instance, open maps to _open. You must explicitly link with OLDNAMES.LIB only when you compile with the following combinations of command-line options:
/Zl (omit default library name from object file) and /Ze (the default — use Microsoft extensions)
/link (linker-control), /NOD (no default-library search), and /Ze
For more information about compiler command-line options, see Compiler Reference.