SQM or SQM-L

I dont see the type of meter defined clearly in recent posts. I use the SQM-L. This has a reduced area of measurement. The SQM would appear to have a wider field and therefore lower readings. When i look at the Institute of Lighting Engineers Guidance Note 1 (01/2021), quoted by many building developments, the ambient light levels are split into Environmental Zones using an “SQM”. I am in category E2: Rural (low district brightness) in relatively dark outer suburban locations.

My zenith SQM-L on moonless nights are between 20.7 and 20.9, and yet the guidance notes give SQM 15-20. Just about strong Moonlight conditions by my measurement. How are developers supposed to understand what a darkness is?

Im grateful to developers doing their best not to make things worse, but the SQM scale they are working within are rather wide. I hope you can see the attached clip from the Guidance notes.

If i were to re-type the table, i would add 1 unit to all the values so E0 becomes 21.5+. It could be that SQM give 1 unit less scale reading compared to SQM-L. In which case i would understand a little better.