APPENDIX
126
APPENDIX
3. You may opt to apply the terms of the ordinary GNU General
Public License instead of this License to a given copy of the
Library. To do this, you must alter all the notices that refer to
this License, so that they refer to the ordinary GNU General
Public License, version 2, instead of to this License. (If a newer
version than version 2 of the ordinary GNU General Public
License has appeared, then you can specify that version
instead if you wish.) Do not make any other change in these
notices.
Once this change is made in a given copy, it is irreversible for
that copy, so the ordinary GNU General Public License applies
to all subsequent copies and derivative works made from that
copy.
This option is useful when you wish to copy part of the code
of the library into a program that is not a library.
4. You may copy and distribute the library (or a portion or deriv-
ative of it, under Section 2) in object code or executable form
under the terms of Sections 1 and 2 above provided that you
accompany it with the complete corresponding machine-
readable source code, which must be distributed under the
terms of sections 1 and 2 above on a medium customarily
used for software interchange.
If distribution of object code is made by offering access to
copy from a designated place, then offering equivalent access
to copy the source code from the same place satisfies the
requirement to distribute the source code, even though third
parties are not compelled to copy the source along with the
object code.
5. A program that contains no derivative of any portion of the
Library, but is designed to work with the Library by being
compiled or linked with it, is called a “work that uses the
Library”. Such a work, in isolation, is not a derivative work of
the Library, and therefore falls outside the scope of this
license.
However, linking a “work that uses the library” with the Library
creates an executable that is a derivative of the Library
(because it contains portions of the library), rather than a
“work that uses the library”. The executable is therefore cov-
ered by this license. Section 6 states terms for distribution of
such executable.
When a “work that uses the library” uses material from a head-
er file that is part of the library, the object code for the work
may be a derivative work of the library even though the source
code is not.
Whether this is true is especially significant if the work can be
linked without the library, or if the work is itself a library. The
threshold for this to be true is not precisely defined by law.
If such an object file uses only numerical parameters, data
structure layouts and accessories, and small macros and small
inline functions (ten lines or less in length), then the use of
the object file is unrestricted, regardless of whether it is legal-
ly a derivative work. (Executable containing this object code
plus portions of the library will still fall under Section 6.)
Otherwise, if the work is a derivative of the library, you may
distribute the object code for the work under the terms of
Section 6. Any executable containing that work also fall under
Section 6, whether or not they are linked directly with the
library itself.
6. As an exception to the sections above, you may also combine
or link a "work that uses the library" with the library to pro-
duce a work containing portions of the library, and distribute
that work under terms of your choice, provided that the terms
permit modification of the work for the customer's own use
and reverse engineering for debugging such modifications.
You must give prominent notice with each copy of the work
that the library is used in it and that the Library and its use
are covered by this license. You must supply a copy of this
license. If the work during execution displays copyright
notices, you must include the copyright notice for the library
among them, as well as a reference directing the user to the
copy of this license. Also, you must do one of these things:
a) Accompany the work with the complete corresponding
machine-readable source code for the library including
whatever changes were used in the work (which must be
distributed under Sections 1 and 2 above); and, if the work
is an executable linked with the Library, with the complete
machine-readable “work that uses the Library”, as object
code and/or source code, so that the user can modify the
library and then relink to produce a modified executable
containing the modified library. (It is understood that the
user who changes the contents of definitions files in the
library will not necessarily be able to recompile the appli-
cation to use the modified definitions.)
b) Use a suitable shared library mechanism for linking with the
library. A suitable mechanism is one that (1) uses at run time
a copy of the library already present on the user’s computer
system, rather than copying library functions into the exe-
cutable, and (2) will operate properly with a modified version
of the library, if the user installs one, as long as the modified
version is interface-compatible with the version that the
work was made with.
c) Accompany the work with a written offer, valid for at least
three years, to give the same user the materials specified in
Subsection 6, above, for a charge no more than the cost of
performing this distribution.
d) If distribution of the work is made by offering access to
copy from a designated place, offer equivalent access to
copy the above specified materials from the same place.
e) Verify that the user has already received a copy of these
materials or that you have already sent this user a copy.