AutoCAD supports dynamic dimensions through callback function pointers on the AcDbGripData objects returned by the AcDbEntity::getGripPoints() function. Dynamic block applications that implement the AcDbAppEntityGrips protocol reactor may support dynamic dimensions by providing the same callback pointers and dimension entities through their returned AcDbGripData objects. The dynamic block infrastructure provides no additional means of elaborating dynamic dimensions while grip-editing dynamic blocks.
See the ObjectARX Reference for additional information on the AcDbEntity::getGripPoints(), AcDbEntity:: moveGripPointsAt(), AcDbAppEntityGrips::getGripPoints(), and AcDbAppEntityGrips::moveGripPointsAt() functions, as well as the AcDbGripData class.