diff --git a/README.md b/README.md
index d5e48e8..528cd17 100644
--- a/README.md
+++ b/README.md
@@ -125,25 +125,44 @@ rules and worked examples.
 
 ## Pattern syntax
 
-Each line in `blacklist` and `whitelist` is a pattern in one of the
-following forms (the same forms that qBittorrent's excluded file names
-accepts, since that is where blacklist patterns end up via Cleanuparr's
-Blocklist Sync):
+The patterns in `blacklist` and `whitelist` are consumed by two different
+tools with different capabilities. Use only the common subset (wildcards)
+to ensure patterns work everywhere.
 
-| Form | Example | Matches |
+### qBittorrent (via Blocklist Sync)
+
+qBittorrent's excluded file names field uses Qt glob wildcards:
+
+| Pattern | Example | Matches |
 |---|---|---|
-| `*example` | `*.srt` | File name ends with `example` |
-| `example*` | `sample*` | File name starts with `example` |
-| `*example*` | `*sample*` | File name contains `example` |
-| `example` | `RARBG.txt` | File name is exactly `example` |
-| `regex:<regex>` | `regex:.*\.srt$` | File name matches the regex |
+| `*` | `*.srt` | Zero or more characters |
+| `?` | `*.r??` | Exactly one character |
+| `[abc]` | `*.[rs]00` | One character from the set |
+| `[a-z]` | `*.[r-z]??` | One character in the range |
+| `[!abc]` | `*.[!m]??` | One character NOT in the set |
+| Literal | `VOSTFR` | Exact match |
+
+Regex, backslashes, and anchors (`^`, `$`, `\d`, `(?i)`) are **not
+supported** by qBittorrent and will be silently ignored.
+
+### Cleanuparr Malware Blocker (Sonarr/Radarr queue)
+
+Cleanuparr's Malware Blocker supports all the wildcard forms above plus
+regex with the `regex:` prefix:
+
+```
+regex:.*\.srt$
+```
+
+Regex patterns only work in Cleanuparr's Malware Blocker. They do not
+work when pushed to qBittorrent via Blocklist Sync.
+
+### Merge script
 
 The merge script subtracts the whitelist from the blacklist as **exact
 strings**, not by pattern semantics. To remove a pattern from the
 blacklist, the whitelist line must be byte-for-byte identical to the
-blacklist line. `*.srt` in the whitelist strips `*.srt` from the
-blacklist; it does **not** strip `regex:.*\.srt$` even though both
-patterns describe the same files. See
+blacklist line. See
 [Lists](https://git.hisp.no/arr/blocklists/wiki/Lists) for the full rules.
 
 ## Sync schedule