Since the late start of the 2000s schools in the UK have used an absolute, stepped levelling system of numbers (typically 1 to 9) with sub-level gradations a,b and c - with "a" being the highest, e.g.:
1c, 1b, 1a 2c, 2b, 2a 3c, 3b, etc.
Pupil Asset offers full support for these, and their underlying point scores for recording attainment and measuring progress.
Pupil Asset Tracker and MIS also support plus or in-between levels for finer gradations of leveling.