diff --git a/internals.md b/internals.md
index 052082a..8a0a635 100644
--- a/internals.md
+++ b/internals.md
@@ -52,7 +52,8 @@ None of the terminals I tested implement the proposed spec fully, and the exact
 behaviour is subject to ongoing discussion in the freedesktop.org terminal
 working group. Support for this mode should therefore be considered best-effort
 at the moment, especially when support for Brahmic, Arabic, and some east asian
-scripts is required.
+scripts is required. If you just want your emoji family to be 2 columns wide,
+this mode works well enough right now.
 
 This library does the following:
 
@@ -68,7 +69,8 @@ This library does the following:
 Additionally, in the extended mode, the following rules apply:
 
 - If a grapheme cluster contains two or more non-spacing non-zero-width
-  codepoints, its width is wide.
+  codepoints, its width is wide. "Spacing" codepoints in this context are all
+  codepoints with a `General_Category` of `Spacing_Mark`.
 
 This rule makes the width reported by this library across Erlang and Nodejs more
 stable (Unicode version differences, see above), as well as closer match the
@@ -101,6 +103,10 @@ All other codepoints are **narrow**.
 
 # Testing
 
-I currently test against VTE (mainly gnome-terminal), Windows Terminal, Kitty, and foot for mode 2027 support.
+I currently test against VTE (mainly gnome-terminal), Windows Terminal, Kitty,
+and foot for mode 2027 support. I also test on Contour since they originally
+proposed the mode 2027 spec; however, they use a custom Unicode library that I
+don't trust fully.
 
-When reporting a mismatch, please include which terminal and the escaped codepoints. Gitlab/Discord sometimes like to strip certain modifiers.
+When reporting a mismatch, please include which terminal and the escaped
+codepoints. Gitlab/Discord sometimes like to strip certain modifiers.
diff --git a/src/string_width.gleam b/src/string_width.gleam
index 34a8409..b2d4365 100644
--- a/src/string_width.gleam
+++ b/src/string_width.gleam
@@ -579,7 +579,7 @@ pub fn limit_with(
 /// Replace all tab characters found in the string with the amount of spaces
 /// that this tab would have had otherwise.
 ///
-/// This makes it save to prepend to a line, without changing the spacing produced
+/// This makes it safe to prepend to a line, without changing the spacing produced
 /// by tabs anymore.
 ///
 /// ### Examples