Grass:
Go to Help > ArchiCAD 11 Goodies, and download the Grid Tool, install, and restart ArchiCAD. Then go to Work Environment > Tool Schemes > Tool Settings Dialog Boxes > Section Tool and make the Grid Tool visible.
From the ArchiCAD 12 New Features List:
Grid Tool
The Grid Tool allows you to place Grid elements individually or in a Grid System. The Grid Tool creates a custom local Grid whose elements are part of the model and serve as an editable framework for placing multiple elements or for identifying locations in the model.
See The Grid Tool in ArchiCAD Help.
Note: The Grid Tool was included in some localized earlier versions of ArchiCAD; as of ArchiCAD 12, it is now a standard part of the package.
David