The timing report generated by the Lattice Diamond Place and Route Tools report a timing coverage %. This number tells the user how complete their timing report is. Some customers require 100% timing coverage to ensure their designs are fully timed. In some cases the user cannot get 100% timing coverage.
Achieving 100% timing coverage is dependent on the type of BLOCK used.
For a global BLOCK, such as BLOCK INTERCLOCKDOMAIN PATHS and BLOCK PATH FROM/TO CLKNET, some of these connections in these blocked paths may be reported as uncovered. In this case trace will not achieve 100% coverage.
However, if the block preference is a specific one for start/end points, such as BLOCK PATH FROM/TO CELL/PORT, full path tracing is done and these connections will not be reported as uncovered anymore.