1 files changed, 9 insertions, 3 deletions
diff --git a/docs/design.md b/docs/design.md
index bf8eca0..9479914 100644
--- a/docs/design.md
+++ b/docs/design.md
@@ -274,8 +274,12 @@ UTF-8 is replaced by U+FFFD before folding.
    rule matches only when its condition is true; an unknown exclude holds
    (§4.6). While no earlier rule has matched a file but one could not be
    decided, `(matched)` is unknown too, so a catch-all
-   `(not (matched))` does not take the file. `explain` shows an unknown test as `?`. A format with no text (§6,
-   "anything else") is not a failure: `content` is false, silently.
+   `(not (matched))` does not take the file, and a rule with `(stop)` whose
+   condition is unknown ends the search for the file. A `duplicate` test
+   whose lookup fails is unknown in the same way (an exclude holds, marked
+   "(duplicate check failed)"). `explain` shows an unknown test as `?` and an
+   undecided rule as "undecided". A format with no text (§6, "anything
+   else") is not a failure: `content` is false, silently.
 
 ### 5.5 Duplicates
 
@@ -450,7 +454,9 @@ Captures come from the first `name` test, not inside a `not`, that was true
 while evaluating this rule. Tests of equal cost keep their written order, so
 "first" is well defined. `krino check` rejects a rule that uses `{N}` unless
 every such `name` test in it has at least N groups, and a rule that uses
-`{N}` with no `name` test at all.
+`{N}` with no `name` test at all. It also rejects any placeholder that
+could never expand: an unknown name, `{mtime}` or `{now}` without a format,
+an unknown format code, `{0}`, `{10}` and up, an unclosed `{`.
 
 With `fold` on, a `name` test matches the folded name, but its captures are
 the original name's characters: `(name "^(.+)-faktura")` on