diff --git a/readme.md b/readme.md
index 7032663..1317f27 100644
--- a/readme.md
+++ b/readme.md
@@ -50,5 +50,8 @@ STAR is specialized for atproto MST storage, and best-suited for serializing com
 
 - It should work for "CAR slices" -- contiguous narrowed partial trees that may omit content before and/or after a specific key. (CIDS referencing missing nodes at the boundaries cannot be eliminated)
 
-- It's desireable to be able to archive complete *subtrees*, so enforcing a well-formed atproto commit as the header might not be sufficient on its own. (subtrees could be stored as CAR slices so this may be unnecessary)
+  - It's desireable to be able to archive complete *subtrees*, so enforcing a well-formed atproto commit as the header might not be sufficient on its own. (subtrees could be stored as CAR slices so this may be unnecessary)
 
+- It *might* be interesting to allow arbitrary sparse trees. Not sure yet.
+
+- It's not suitable for firehose commit CARs, which need to include blocks that aren't in a strict single MST.