This constant determines whether the osOpenMailbox function is included or excluded during compilation. The function is compiled if the constant value is 1 and omitted when the value is 0.

If this constant is not defined, it defaults to 1 and the function is included in the output code. If all osOpen* functions are unused, the system will ignore object names, and the code dedicated to name management will be removed. This serves to reduce the final size of the output code. For more information on object naming and opening procedures, please refer to the system objects management section.