diff --git a/docs/getting_started/folders_and_files/files.md b/docs/getting_started/folders_and_files/files.md
index 4a82adb3..6ca7184e 100644
--- a/docs/getting_started/folders_and_files/files.md
+++ b/docs/getting_started/folders_and_files/files.md
@@ -48,7 +48,8 @@ Source: [Datalad RDM course](https://psychoinformatics-de.github.io/rdm-course/0
Entities are composed of key-value pairs separated by underscores
There is a limited set of suffixes for each data type (anat, func, eeg, …)
For a given suffix, some entities are required and some others are [optional].
- Keys, value and suffixes can only contain letters and/or numbers.
+ Entity keys and suffixes can only contain letters and/or numbers.
+ Entity values can only contain letters and/or numbers and/or the "+" character.
Entity key-value pairs have a specific order in which they must appear in filename.
Some entities key-value can only be used for
derivative data.