The ispLEVER Classic software employs three types of constraint files: Lattice constraint input file (.lci), Lattice constraint temporary file (.lct), and Lattice constraint output file (.lco).
The .lci file consists of two types: the parent .lci file and the project .lci file. The parent .lci file, located in the /config directory, is used to specify optimization and hardware-specific parameters. When you create a new project, the software will generate a project .lci file in the project folder. It calls a parent .lci file and can contain user-specified constraints. If you do not specify any constraints, it defaults to the values in the parent file.
The .lct file is the temporary working copy of the .lci file. For example, when you set constraints in the Constraint Editor, the new assignments will first be written to the .lct file. They will not appear in the .lci file until after you have saved the project.
The .lci file is synchronized with the .lct file after each Save. The .lco file is automatically created after you run the design. This file contains the constraints output from the design run, such as post-fit pinouts, and so on. If you backannotate constraints using the Tools menu of the Project Navigator, the constraints output in the .lco file will be written back to the .lct file.