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+{\rtf1\ansi\ansicpg1252\cocoartf949\cocoasubrtf460
+{\fonttbl\f0\fmodern\fcharset0 Courier;}
+{\colortbl;\red255\green255\blue255;}
+\pard\tx560\tx1120\tx1680\tx2240\tx2800\tx3360\tx3920\tx4480\tx5040\tx5600\tx6160\tx6720\sl264\slmult1\ql\qnatural\pardirnatural
+
+\f0\fs28 \cf0 Sometimes a commodity has several forms which are all equivalent.  An\
+example of this is time.  Whether tracked in terms of minutes, hours\
+or days, it should be possible to convert between the various forms.\
+Doing this requires the use of commodity equivalencies.\
+\
+For example, you might have the following two postings, one which\
+transfers an hour of time into a @samp\{Billable\} account, and another\
+which decreases the same account by ten minutes.  The resulting report\
+will indicate that fifty minutes remain:\
+\
+@smallexample\
+2005/10/01 Work done for company\
+    Billable:Client                 1h\
+    Project:XYZ\
+    \
+2005/10/02 Return ten minutes to the project\
+    Project:XYZ                    10m\
+    Billable:Client\
+@end smallexample\
+\
+Reporting the balance for this ledger file produces:\
+\
+@smallexample\
+       50.0m  Billable:Client\
+      -50.0m  Project:XYZ\
+@end smallexample\
+\
+This example works because ledger already knows how to handle seconds,\
+minutes and hours, as part of its time tracking support.  Defining\
+other equivalencies is simple.  The following is an example that\
+creates data equivalencies, helpful for tracking bytes, kilobytes,\
+megabytes, and more:\
+\
+@smallexample\
+C 1.00 Kb = 1024 b\
+C 1.00 Mb = 1024 Kb\
+C 1.00 Gb = 1024 Mb\
+C 1.00 Tb = 1024 Gb\
+@end smallexample\
+\
+Each of these definitions correlates a commodity (such as @samp\{Kb\})\
+and a default precision, with a certain quantity of another commodity.\
+In the above example, kilobytes are reporetd with two decimal places\
+of precision and each kilobyte is equal to 1024 bytes.\
+\
+Equivalency chains can be as long as desired.  Whenever a commodity\
+would report as a decimal amount (less than @samp\{1.00\}), the next\
+smallest commodity is used.  If a commodity could be reported in terms\
+of a higher commodity without resulting to a partial fraction, then\
+the larger commodity is used.}
+\ No newline at end of file