Index: /trunk/FACT++/www/viewer/index.html
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--- /trunk/FACT++/www/viewer/index.html	(revision 17702)
+++ /trunk/FACT++/www/viewer/index.html	(revision 17703)
@@ -333,4 +333,13 @@
 exactly is retruned by proc (an array, or an array with sub-arrays).
 
+<H3>What is the data?</H3>
+The data are all data files found in disks in La Palma (to be precise:
+on daq's disks). The data is raw-data but with the most recent 
+DRS calibration (only the 1024-cell offset calibration) 
+applied, while the application is done in intergers, i.e. the
+fractional part of the calibration constant is removed. 
+(This is basically what is written in our FITS files as part of the
+lossless compression process). No spike or jump removal is applied.
+
 <H3>The editor</H3>
 Key bindings of the editor can be found at