Unable to answer "What’s the identification number here?" – An Post – https://osm.org/node/6374764811 via StreetComplete 57.3:

There are two boxes with codes 
WRD0190A and WRD0189A

Attached photo(s):
https://westnordost.de/p/215652.jpg
https://westnordost.de/p/215653.jpg
https://westnordost.de/p/215654.jpg