diff --git a/etc/lines.list b/etc/lines.list
index 5e9c599..ac7217b 100644
--- a/etc/lines.list
+++ b/etc/lines.list
@@ -1,24 +1,27 @@
 # common transitions LMT might see
+# columns:   frequency (GHz)  formula transition
 
 #  The CO ladder
-110.2013543 13co1-0
-115.2712018   co1-0
-220.39868   13co2-1
-230.53800     co2-1
-330.58797   13co3-2
-345.79599     co3-2
-461.04077     co4-3
-576.26793     co5-4
-691.47308     co6-5
-806.65180     co7-6
-921.79970     co8-7
-1036.912      co9-8
+110.2013543 13co 1-0
+115.2712018   co 1-0
+220.39868   13co 2-1
+230.53800     co 2-1
+330.58797   13co 3-2
+345.79599     co 3-2
+461.04077     co 4-3
+576.26793     co 5-4
+691.47308     co 6-5
+806.65180     co 7-6
+921.79970     co 8-7
+1036.912      co 9-8
+
+112.35928 C17O 1-0
+109.78218 C18O 1-0
+219.56036 C18O 2-1
 
 # other random things to be sorted out
 
 89.18853 HCO+
-115.2712 CO
-230.538 CO
 97.98095 CS
 90.66356 HNC
 271.98111 HNC
@@ -76,14 +79,6 @@
 113.19128 CN
 86.34016 H13CN
 
-112.35928 C17O
-
-110.20135 13CO
-220.39868 13CO
-
-
-109.78218 C18O
-219.56036 C18O
 
 72.40909 H2CO
 72.83795 H2CO