User's Manual

146
You may charge a fee for the physical act of transferring a copy,
and you may at your option offer warranty protection in ex
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change for a fee.
2. You may modify your copy or copies of the Program or any por
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tion of it, thus forming a work based on the Program, and copy
and distribute such modifications or work under the terms of
Section 1 above, provided that you also meet all of these condi
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tions:
a) You must cause the modified files to carry prominent notic
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es stating that you changed the files and the date of any change.
b) You must cause any work that you distribute or publish,
that in whole or in part contains or is derived from the Program
or any part thereof, to be licensed as a whole at no charge to all
third parties under the terms of this License.
c) If the modified program normally reads commands inter
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actively when run, you must cause it, when started running for
such interactive use in the most ordinary way, to print or display
an announcement including an appropriate copyright notice
and a notice that there is no warranty (or else, saying that you
provide a warranty) and that users may redistribute the program
under these conditions, and telling the user how to view a copy
of this License. (Exception: if the Program itself is interactive
but does not normally print such an announcement, your work
based on the Program is not required to print an announce
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ment.)