Symbols for gschem, the schematic editor, part of the gEDA suite.

Following symbols are released under the "GPL v2+" license and unlimited
usage, for more information see the paragraph below and the "LICENSE"
file in this repository.

I Added a directory structure to reflect the usage of the symbol.

"components" for component symbols (heavy).

"generic" for generic components (light).

"ghdl" for schematic entry of VHDL logic (specific for GHDL).

"hydraulics" for hydraulical circuits.

"installation" for floor plans of houses and other real estate.

"ladder" for ladder diagram symbols.

"mechanical" for references in schematics to mechanical entities.

"network" for computer networks.

"piping" for Piping and Process & Instrumentation Diagrams.

"power" for reference to power/ground symbols.

"structural" for representation of schematized steel structures.

"sheets" template drawing sheets.

"units" for representation of sub assemblies.

"vhdl" for schematic entry of VHDL logic.


A word about Licensing on symbols.
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All software components of gEDA/gaf are released under the GNU General
Public License (GPL) version 2 or later. However, some confusion exists
about the schematic symbols. What license do they use? Will GPL symbols
“infect” your design, thereby requiring you to release your design to
the public? If you modify the symbols, must you release the modified
versions under the GPL?

The goal of the gEDA Project is to provide an open-source EDA Suite
which may be used for non-commercial as well as commercial projects. Our
tools are aimed for use by students, hobbyists, educators, consultants,
and - yes - corporate engineers. We are not interested in exerting any
control over your designs, or forcing you to reveal proprietary
information contained in your designs.

Symbols are similar to the font files used in document processing
software – they are graphical objects used to express your ideas. We
want you to retain control of your own ideas (your design), while the
gEDA Project retains a say in how you redistribute the symbols themselves.

There are three ways a symbol might be distributed:

  1. As part of a symbol library, or individually as a .sym file 
     (i.e. as a symbol itself).
  2. Embedded in a .sch file (i.e. part of the soft, or editable copy of
     a design).
  3. The resulting graphical expression on a schematic diagram (i.e. as
     part of the hard, or non-editable copy of a design).

There is a distinction between cases 1 and (2, 3). In case 1, the object
of interest is the symbol library (or individual symbol) itself. In case
(2, 3), the object of interest is the design. Some label case 1
“distribution”, and case (2, 3) “use” of the symbol.

Our goals for the symbols are:

  * We wish to distribute the symbols under a licencing scheme which
    encourages that you give back to the community if you redistribute
    the the symbols themselves - whether modified or unmodified. This is
    case 1 distribution. The GPL ensures this.

  * We wish to specifically prohibit anybody from building gEDA's
    symbols into their *software* products, and then place restrictions
    on how the resulting product may be used. If you bundle gEDA symbols
    - whether modified or unmodified - into your software and then
    distribute it, then you must allow for the software's (and symbols')
    continued redistribution under the GPL. Again, this is case 1
    distribution; the GPL ensures this.

  * However, we do not wish to “infect” your *electronic* design, or
    force you to release your proprietary design information if you use
    or embed gEDA symbols in your design. This is case (2, 3) use.

The Free Software Foundation has recognized a possible conflict of the
base GPL with the use of fonts - and, by analogy, symbols used in case
(2, 3). Their solution is to use an exemption clause in the GPL which
you explicitly insert for fonts. Read about it here:

http://www.fsf.org/licensing/licenses/gpl-faq.html#FontException

Therefore, using this as a template, all symbols released with gEDA/gaf
are covered under the GPL with the following exception clause:

"As a special exception, if you create a design which uses this symbol,
and embed this symbol or unaltered portions of this symbol into the
design, this symbol does not by itself cause the resulting design to
be covered by the GNU General Public License. This exception does not
however invalidate any other reasons why the design itself might be
covered by the GNU General Public License. If you modify this
symbol, you may extend this exception to your version of the
symbol, but you are not obligated to do so. If you do not
wish to do so, delete this exception statement from your version."

The idea is that case 1 redistribution is covered under the GPL, but
distribution of your design (case (2, 3) is exempt from the GPL. This is
the scheme which the gEDA Project wishes to use for symbol distribution
and use.