diff --git a/README.md b/README.md
index e20d9124..fd2d50a0 100644
--- a/README.md
+++ b/README.md
@@ -5,7 +5,7 @@
 ![](https://img.shields.io/crates/v/hexyl.svg?colorB=00aa88)
 
 `hexyl` is a hex viewer for the terminal. It uses a colored output to distinguish different categories
-of bytes (NULL bytes, printable ASCII characters, ASCII whitespace characters, other ASCII characters and non-ASCII).
+of bytes (NULL bytes, 7-bit printable ASCII, ASCII whitespace, other 7-bit ASCII, and non-ASCII bytes 0x80–0xFF).
 
 ## Preview
 
diff --git a/doc/hexyl.1.md b/doc/hexyl.1.md
index 08730ee4..be31c97c 100644
--- a/doc/hexyl.1.md
+++ b/doc/hexyl.1.md
@@ -14,8 +14,8 @@ hexyl - a command-line hex viewer
 
 **hexyl** is a simple hex viewer for the terminal.
 It uses a colored output to distinguish different categories of bytes (NULL
-bytes, printable ASCII characters, ASCII whitespace characters, other ASCII
-characters and non-ASCII).
+bytes, 7-bit printable ASCII characters, ASCII whitespace characters, other
+7-bit ASCII characters and non-ASCII bytes (0x80–0xFF).
 
 # POSITIONAL ARGUMENTS
 
diff --git a/src/lib.rs b/src/lib.rs
index 48fbc5bd..90db5df3 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -34,9 +34,11 @@ pub enum IncludeMode {
 #[derive(Copy, Clone, Debug, Default, ValueEnum)]
 #[non_exhaustive]
 pub enum CharacterTable {
-    /// Show printable ASCII characters as-is, '⋄' for NULL bytes, ' ' for
-    /// space, '_' for other ASCII whitespace, '•' for other ASCII characters,
-    /// and '×' for non-ASCII bytes.
+    /// Show 7-bit printable ASCII (0x20–0x7E) as-is, '⋄' for NULL bytes, ' '
+    /// for space, '_' for other ASCII whitespace, '•' for other 7-bit control
+    /// characters, and '×' for non-ASCII bytes (0x80–0xFF). Extended/8-bit
+    /// "ASCII" code pages are not shown as glyphs here; use `codepage-437`
+    /// (or another table) if you need that.
     #[default]
     Default,