diff --git a/docs/user/guide.md b/docs/user/guide.md
index b875ab04..16ee5ac3 100644
--- a/docs/user/guide.md
+++ b/docs/user/guide.md
@@ -279,6 +279,39 @@ follow Bitcoin Core v32's maintained
   confirmed.” `--plain` skips card confirmation. Redirected damaged input can
   still require an interactive correction confirmation.
 
+### What `correct` can repair
+
+`correct` repairs one string at a time. Type each unreadable character as `?`.
+It can fix:
+
+- up to 8 unreadable characters or up to 4 wrong ones. One wrong character
+  uses up the room of two unreadable ones, so 6 unreadable and 1 wrong, or 4
+  unreadable and 2 wrong, also work;
+- 13 unreadable characters in a row, or 15 in a long codex32 string (127
+  characters);
+- up to 4 missing characters, up to 4 extra ones, or one of each;
+- one swap of two characters anywhere in the string along with up to 2 wrong
+  ones, or up to 3 swaps of neighboring characters;
+- one missing, extra or swapped character along with up to 3 wrong ones;
+- one or two whole four-character groups missing, extra or swapped, or one
+  group with every character wrong.
+
+It can't fix 9 or more scattered unreadable characters, 5 or more missing
+characters outside whole missing groups, more than 13 unreadable characters in a
+row (15 in a long codex32 string), or two groups that are both wrong. If you
+know which groups are wrong, type their characters as `?`: two groups are then 8
+unreadable characters, which it can fix. Some repairs take the full ten seconds,
+so a slower computer may not finish them, and past this list the search rarely
+succeeds.
+
+If whole groups are missing, give the seed's size with `--bytes`, such as
+`--bytes 32` for a 74-character string. Specifying the size narrows the search
+and can let repairs finish before the deadline.
+
+Filling 13 unreadable characters in a row (15 in a long codex32 string) always
+produces a valid string, but if any other character was mistyped, that string is
+wrong. This is why `correct` asks you to type `YES` before showing it.
+
 ### Advanced: completing missing trailing characters
 
 The correction command can fill trailing erasures when the final characters