TODO updated

TODO.md

@@ -17,3 +17,27 @@
 - PDCI dataset is downloadable as Excel (for selected accessions)
 - WorldClim dataset is downloadable as Excel (for selected accessions)
 
+# TODO Accession Lists
+
+- Make new list from applied filter (limit list size to X)
+- FIXME Blank list does not load and cannot be removed
+- Listing accessions by list (in Browse) needs a better completer
+- A decent user interface
+
+## Set operations ##
+
+- Add set operations: union (A ∪ B), intersection (A ∩ B),
+  complement (A ∖ B, B ∖ A), symmetric difference (A △ B)
+- Temporary (session scoped) sets? -- similar to the existing `SelectionBean`? 
+  Bad idea, big lists needs to sync across the cluster.
+- Should consider making the accession lists a new functionality: create list from
+  selection, but not the other way around. Selection should be a small list, while
+  Accession lists may contain 1,000s of items.
+  
+## Filters and Accession sets ##
+
+Rename "Accession Lists" to "Accession Sets". When the set is created from a filtered
+list of accessions, the filter should be stored with set metadata. This would potentially
+allow for updating the set or identifying missing/new elements.
+
+ 
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