kc3-lang/kc3

diff --git a/doc/1_KC3/1.09_Block.en.md b/doc/1_KC3/1.09_Block.en.md
index e4926a6..7133630 100644
--- a/doc/1_KC3/1.09_Block.en.md
+++ b/doc/1_KC3/1.09_Block.en.md
@@ -6,6 +6,9 @@ It can be passed to a special operator or macro function to
 be evaluated explicitly in C with `env_eval_block` (see
 `libkc3/env_eval.c`).
 
+A block evaluates all its instructions in turn, and returns the value
+of the last expression.
+
 ## 1.9.1 Examples
 
 ```elixir