diff --git a/TODO.md b/TODO.md
index 56855b6..5b4225f 100644
--- a/TODO.md
+++ b/TODO.md
@@ -3,5 +3,7 @@ Improve the PNG interface.
 Global parameters to control encoder settings:
 - Quantization level: quant 0
 - Quantization level: quants 1-63
+  - Constant term
+  - Linear term
 - Number of quants to keep, per tile.
 - Whether to use wide or packed representation for the thumbnail block
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