diff --git a/content/tech/spec/activitypub/shortcomings/collections-underspecced.md b/content/tech/spec/activitypub/shortcomings/collections-underspecced.md
index e002dd9..82d6471 100644
--- a/content/tech/spec/activitypub/shortcomings/collections-underspecced.md
+++ b/content/tech/spec/activitypub/shortcomings/collections-underspecced.md
@@ -23,4 +23,8 @@ what might this imply is needed for activitypub?
 - `orderedBy`?
 	- what about multiple ordering criteria? SQL has `ORDER BY`
 	- actually, is a query language a good fit here?
-- `reversed`? more like `order: Ascending` or `order: Descending`?
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+- `reversed`? more like `order: Ascending` or `order: Descending`?
+
+## querying
+
+how do you tell if an arbitrary object is included in a collection or not? without iterating over the entire collection, that is.
\ No newline at end of file