diff --git a/docs/index.rst b/docs/index.rst
index 284fe5a112feabebf0b457ab72dced94434e56d5..0a59315b30269df8de2af5a08bf460571cf2ec62 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -22,6 +22,7 @@ ATHENA Software
 
    productions/singles
    productions/physics
+   productions/FAQ
 
 
 .. toctree::
diff --git a/docs/productions/FAQ.rst b/docs/productions/FAQ.rst
new file mode 100644
index 0000000000000000000000000000000000000000..9443fc7876a1b84377b671ad08da566a31f8fcf0
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@@ -0,0 +1,19 @@
+Frequently Asked Questions
+==========================
+
+It seems that the `ReconstructedParticles` branches are empty, but used to be filled.
+-------------------------------------------------------------------------------------
+
+`ReconstructedParticles` used to be filled with just smeared info (so analyzers could start developing scripts even if the values in there were not from proper track reconstruction and event building). In the first `acadia` production we had an unexpected issue filling `ReconstructedParticles`, but that should be resolved soon. Plan on having access to the actual momentum from track reconstruction in `ReconstructedParticles` (with exact PID from truth, and energy from momentum and PID).
+
+
+Should the physics working groups plan to use the calorimeter clusters?
+-----------------------------------------------------------------------
+
+We are still working on full event building that will also take into account energy from clusters, so in `acadia` the energy is based on the momentum and truth PID.
+
+
+Which four-vectors should I plan to use?
+----------------------------------------
+
+As for four-vectors, this is somewhat up to you. We are not providing four-vectors in `ReconstructedParticles`. For some particles they will be four-vectors, though: particles without info from either tracking or calorimetry. Depending on the analysis you are performing, you may want to use momentum direction and energy (say, higher energy central electrons) while for others you may want to use momentum direction and momentum magnitude (say, low energy central electrons).