diff --git a/src/search/forms.py b/src/search/forms.py
index 9125e59..a6633c3 100644
--- a/src/search/forms.py
+++ b/src/search/forms.py
@@ -101,6 +101,8 @@ class ColabSearchForm(SearchForm):
                 'q.alt': '*.*',
                 'pf': 'title^2.1 author^1.9 description^1.7',
                 'mm': '2<70%',
+
+                # Date boosting: http://wiki.apache.org/solr/FunctionQuery#Date_Boosting
                 'bf': 'recip(ms(NOW/HOUR,modified),3.16e-11,1,1)^10',
             }
 
--
libgit2 0.21.2