This enables the contents of the macro to be replaced by the exact foundry GDS, which in some cases is required for complex macros with foundry-specific assumptions behind them e.g. SRAMs with OPC (it would also be needed in the case where the foundry isn't providing the macro contents at all).
This enables the contents of the macro to be replaced by the exact foundry GDS, which in some cases is required for complex macros with foundry-specific assumptions behind them e.g. SRAMs with OPC (it would also be needed in the case where the foundry isn't providing the macro contents at all).