--- trunk/doc/exact_match.txt	2004/04/02 23:31:25	298
+++ trunk/doc/exact_match.txt	2004/04/04 20:48:56	299
@@ -27,3 +27,25 @@
 <input type="text" name="v1">
 <input type="hidden" name="e1" value="5">
 
+
+What are bit-masks?
+
+Bit-mask is usage of one byte (8 bits) as 8 separate bits with it's own meaning.
+So, 1 = 2^1, thus it's bit 1. So, for 1-3 we have:
+
+number	bits
+1	01
+2	10
+3	11
+
+For that we are using two bits. If we want to produce wild-card match, we use
+bit 3 (2^3 = 4) so we have:
+
+number	bits
+1	001	begin
+2	010	end
+3	011	begin+end
+4	100	(not used)
+5	101	(4+1) begin+wild-card
+6	110	(4+2) end+wild-card
+7	111	(4+3) begin+end+wild-card