kc3-lang/kc3

diff --git a/doc/1_KC3/1.18_Callable.en.md b/doc/1_KC3/1.18_Callable.en.md
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+# 1.18 Callable
+
+The KC3 `Callable` type is an or-type of `Cfn` and `Fn`.
+
+In any case where you accept a `Fn` or `Cfn` as an argument
+you should use `Callable` as the type.
diff --git a/doc/1_KC3/1.19_Ptr.en.md b/doc/1_KC3/1.19_Ptr.en.md
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+# 1.19 Ptr
+
+In KC3 there should be no use for Ptr type but it's here to stay
+compatible with C's `void *` type.
+
+You can cast from and to a pointer but be careful about correctly
+chaining casts from the same type to the same type.
+
+The only parsable pointer is the NULL pointer :
+
+```elixir
+ikc3> (Ptr) 0
+(Ptr) 0
+```