diff --git a/readme.md b/readme.md
index 6d123af..2c07a33 100644
--- a/readme.md
+++ b/readme.md
@@ -203,9 +203,13 @@ Options for creating a Graph/Data file:
 
 These files do not have a human-readable structure, and are not portable to other programs.
 
-(For portability to other software, turn on GraphML output in the Options menu in interactive mode, or use the `-graphml`
-command line argument. This will produce a .graphml file for the weighted graph, with 
-vertex attributes for sequence, type, and occupancy data.)
+*Optional GraphML output*
+
+For portability of graph data to other software, turn on [GraphML](http://graphml.graphdrawing.org/index.html) output 
+in the Options menu in interactive mode, or use the `-graphml`command line argument. This will produce a .graphml file 
+for the weighted graph, with vertex attributes for sequence, type, and occupancy data. This graph contains all the data 
+necessary for the BiGpairSEQ matching algorithm. It does not include the data to measure pairing accuracy; for that, 
+compare the matching results to the original Cell Sample .csv file.
 
 ---