diff --git a/docs/ics_format.txt b/docs/ics_format.txt
index c65059b..8c979fe 100644
--- a/docs/ics_format.txt
+++ b/docs/ics_format.txt
@@ -35,6 +35,9 @@ according to the unfolding procedure described above.
 
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+Colons seem to be allowed in the "value" so you can't split by colon.
+You have to split by "\r\n" but unfold the lines before.
+
 Observation of different ics files from different sources
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