diff --git a/docs/features/cmdb-import.md b/docs/features/cmdb-import.md
index 7c8bfa64..bf8f9527 100644
--- a/docs/features/cmdb-import.md
+++ b/docs/features/cmdb-import.md
@@ -120,7 +120,12 @@ CSV files are not accepted.
 **Placeholder values.** The CMDB sheets fill an empty `BNN Classificatie`
 with `NB` ("niet bekend"); that is read as empty. Dates are stored as the
 file has them: the CMDB's 2036-01-01 in `End-of-Life Functioneel` is imported
-as 2036-01-01.
+as 2036-01-01. The CMDB writes that date when TOPdesk has no end-of-life date,
+so it is a stand-in for "no date". It is stored as the phase-out date of the
+usage and shown like any real one, and the usage reads as "Phased out"
+once that date is reached. A re-import with **Update existing records** on
+fills the date where it was left empty before. It also replaces a different
+date stored there, including one set by hand.
 
 ### Columns and where they go