Altium Designer's FPGA design environment supports a range of constraints that are device independent. However, since not all FPGA families share the same technology there are also vendor constraints that can be used. The Xilinx tools support a range of constraints that allow you to take advantage of internal technology and other design options. For detailed information on Xilinx FPGA constraints refer to the Xilinx Constraints Guide.
Xilinx constraints can be included with your design by adding the Xilinx User Constraint (UCF) files to the FPGA project. Multiple constraint files can be added, enable their use in the project by disabling the Ignore UCF file option, accessed by clicking the Options button associated with the Translate Design stage of the Build process.