No real question, but I want to share some insights for my Belgian colleagues.

In FME, there are two 31370 coordinate systems: EPSG:31370 and Belge_72.Lambert_72_FME. They are exactly the same, except for the Esri WKT Description. The first one contains false easting and northing up to 5 decimals, the second one only three (like the OGC WKT).

Until ArcGIS 10.6, you have to use the EPSG:31370, with the additional decimals.

Starting from ArcGIS 10.7, ESRI changed the description of the coordinate system and applied the OGC values with 3 decimals.

Opening a filegeodatabase with EPSG:31370 in ArcGIS 10.7 leads to a 'custom coordinate system', not recognised by the software. Using the Belge_72.Lambert_72_FME coordinate system in FME avoids this issue.

I hope this post will help some people saving some time.