A macro variable is a preprocessor variable whose value is specified when the application is processed by the OpenROAD preprocessor. If you specify macro variable names in your script, the corresponding value is substituted by the preprocessor before compiling.

OpenROAD provides built-in macro variables for your use. You can also create macro variables either in the frame script or by using the Macro Variable Editor. Macro variables let you compile your code conditionally; they also simplify code maintenance.