Chapter 5 - A ppendix
Appendix A - G NU G eneral P ublic L icense
Version 2 , J une 1 991 C opyright ( C) 1 989, 1 991 F ree S oftware F oundation, I nc.
59 T emple P lace, S uite 3 30, B oston, M A 0 2111-1307 U SA
Everyone i s p ermitted t o c opy a nd d istribute v erbatim c opies o f t his l icense d ocument, b ut c hanging i t i s n ot
allowed.
Preamble
The l icenses f or m ost s oftware a re d esigned t o t ake a way y our f reedom t o s hare a nd c hange i t. B y c ontrast, t he
GNU G eneral P ublic L icense i s i ntended t o g uarantee y our f reedom t o s hare a nd c hange f ree s oftware--to m ake
sure t he s oftware i s f ree f or a ll i ts u sers. T his G eneral P ublic L icense a pplies t o m ost o f t he F ree S oftware
Foundation's s oftware a nd t o a ny o ther p rogram w hose a uthors c ommit t o u sing i t. ( Some o ther F ree S oftware
Foundation s oftware i s c overed b y t he G NU L ibrary G eneral P ublic L icense i nstead.) Y ou c an a pply i t t o y our
programs, t oo.
When w e s peak o f f ree s oftware, w e a re r eferring t o f reedom, n ot p rice. O ur G eneral P ublic L icenses a re d esigned
to m ake s ure t hat y ou h ave t he f reedom t o d istribute c opies o f f ree s oftware ( and c harge f or t his s ervice i f y ou
wish), t hat y ou r eceive s ource c ode o r c an g et i t i f y ou w ant i t, t hat y ou c an c hange t he s oftware o r u se p ieces o f i t
in n ew f ree p rograms; a nd t hat y ou k now y ou c an d o t hese t hings.
To p rotect y our r ights, w e n eed t o m ake r estrictions t hat f orbid a nyone t o d eny y ou t hese r ights o r t o a sk y ou t o
surrender t he r ights. T hese r estrictions t ranslate t o c ertain r esponsibilities f or y ou i f y ou d istribute c opies o f t he
software, o r i f y ou m odify i t.
For e xample, i f y ou d istribute c opies o f s uch a p rogram, w hether g ratis o r f or a f ee, y ou m ust g ive t he r ecipients a ll
the r ights t hat y ou h ave. Y ou m ust m ake s ure t hat t hey, t oo, r eceive o r c an g et t he s ource c ode. A nd y ou m ust
show t hem t hese t erms s o t hey k now t heir r ights.
We p rotect y our r ights w ith t wo s teps: ( 1) c opyright t he s oftware, a nd ( 2) o ffer y ou t his l icense w hich g ives y ou
legal p ermission t o c opy, d istribute a nd/or m odify t he s oftware.
Also, f or e ach a uthor's p rotection a nd o urs, w e w ant t o m ake c ertain t hat e veryone u nderstands t hat t here i s n o
warranty f or t his f ree s oftware. I f t he s oftware i s m odified b y s omeone e lse a nd p assed o n, w e w ant i ts r ecipients
to k now t hat w hat t hey h ave i s n ot t he o riginal, s o t hat a ny p roblems i ntroduced b y o thers w ill n ot r eflect o n t he
original a uthors' r eputations.
F inally, a ny f ree p rogram i s t hreatened c onstantly b y s oftware p atents. W e w ish t o a void t he d anger t hat
redistributors o f a f ree p rogram w ill i ndividually o btain p atent l icenses, i n e ffect m aking t he p rogram p roprietary.
To p revent t his, w e h ave m ade i t c lear t hat a ny p atent m ust b e l icensed f or e veryone's f ree u se o r n ot l icensed a t
all.
The p recise t erms a nd c onditions f or c opying, d istribution a nd m odification f ollow.
GNU G ENERAL P UBLIC L ICENSE T ERMS A ND C ONDITIONS F OR C OPYING, D ISTRIBUTION A ND M ODIFICATION
0. T his L icense a pplies t o a ny p rogram o r o ther w ork w hich c ontains a n otice p laced b y t he c opyright h older s aying
it m ay b e d istributed u nder t he t erms o f t his G eneral P ublic L icense. T he " Program", b elow, r efers t o a ny s uch
program o r w ork, a nd a " work b ased o n t he P rogram" m eans e ither t he P rogram o r a ny d erivative w ork u nder
copyright l aw: t hat i s t o s ay, a w ork c ontaining t he P rogram o r a p ortion o f i t, e ither v erbatim o r w ith m odifications
and/or t ranslated i nto a nother l anguage. ( Hereinafter, t ranslation i s i ncluded w ithout l imitation i n t he t erm
"modification".) E ach l icensee i s a ddressed a s " you". A ctivities o ther t han c opying, d istribution a nd m odification a re
not c overed b y t his L icense; t hey a re o utside i ts s cope. T he a ct o f r unning t he P rogram i s n ot r estricted, a nd t he
output f rom t he P rogram i s c overed o nly i f i ts c ontents c onstitute a w ork b ased o n t he P rogram ( independent o f
having b een m ade b y r unning t he P rogram). W hether t hat i s t rue d epends o n w hat t he P rogram d oes.
1. Y ou m ay c opy a nd d istribute v erbatim c opies o f t he P rogram's s ource c ode a s y ou r eceive i t, i n a ny m edium,
provided t hat y ou c onspicuously a nd a ppropriately p ublish o n e ach c opy a n a ppropriate c opyright n otice a nd
disclaimer o f w arranty; k eep i ntact a ll t he n otices t hat r efer t o t his L icense a nd t o t he a bsence o f a ny w arranty;
and g ive a ny o ther r ecipients o f t he P rogram a c opy o f t his L icense a long w ith t he P rogram. Y ou m ay c harge a f ee
for t he p hysical a ct o f t ransferring a c opy, a nd y ou m ay a t y our o ption o ffer w arranty p rotection i n e xchange f or a