### OLD Module Definition Statement

Syntax: | Parameters:
OLD'[dir] name' | Name of DLL

Use the OLD statement when you create a dynamic link library (DLL) to preserve compatibility with an older version of the DLL. When you provide the name of the old DLL, specify the directory it is in as well, if it is not in the current working directory.

The linker compares exported data constructs or functions in the old DLL with exported data constructs or functions in the current DLL. If the old data construct or function has an ordinal value assigned to it, the linker assigns the ordinal value to the equivalent data construct or function in the new DLL.

If another run-time module called functions or referenced data from the old DLL by ordinal value, it can continue calling functions and referencing data from the new DLL using the same ordinal values.

The linker will only assign the old ordinal value to a data construct or function when:

- The data construct or function name in the old DLL matches the data construct or function name in the new DLL exactly
- The old data construct or function has an ordinal value assigned to it
- The new data construct or function does not already have an ordinal value assigned to it.

Summary of Module Definition Statements