Copyrigh t (C) 2000,2001,2002 Fre e Softw are Foundation, Inc. 51 Frank l in St, Fifth Fl oor, Bos ton, M A 021101301 U SA Eve ryone is pe rm itte d to copy and dis tribute ve rbatim copie s of th is l ice ns e docum e nt, but ch anging it is not al l ow e d.
Th e purpose of th is Lice nse is to m ak e a m anual, te xtbook , or oth e r functionaland use fuldocum e nt "fre e " in th e se nse of fre e dom : to assure e ve ryone th e e ffe ctive fre e dom to copy and re distribute it, w ith or w ith out m odifying it, e ith e r com m e rcially or noncom m e rcially. Se condarily, th is Lice nse pre se rve s for th e auth or and publish e r a w ay to ge t cre dit for th e ir w ork , w h ile not be ing conside re d re sponsible for m odifications m ade by oth e rs. Th is Lice nse is a k ind of "copyleft", w h ich m e ans th at de rivative w ork s of th e docum e nt m ust th e m se lve s be fre e in th e sam e se nse. It com plem e nts th e GNU Ge ne ral Public Lice nse, w h ich is a copyleft lice nse de signe d for fre e softw are. W e h ave de signe d th is Lice nse in orde r to use it for m anuals for fre e softw are, be cause fre e softw are ne e ds fre e docum e ntation: a fre e program sh ould com e w ith m anuals providing th e sam e fre e dom s th at th e softw are doe s. But th is Lice nse is not lim ite d to softw are m anuals;it can be use d for any te xtualw ork , re gardless of subje ct m atte r or w h e th e r it is publish e d as a printe d book . W e re com m e nd th is Lice nse principally for w ork s w h ose purpose is instruction or re fe re nce.
Th is Lice nse applie s to any m anualor oth e r w ork , in any m e dium , th at contains a notice place d by th e copyrigh t h olde r saying it can be distribute d unde r th e te rm s of th is Lice nse. Such a notice grants a w orld-w ide, royalty-fre e lice nse, unlim ite d in duration, to use th at w ork unde r th e conditions state d h e re in. Th e "D ocum e nt", be low , re fe rs to any such m anualor w ork . Any m e m be r of th e public is a lice nse e, and is addre sse d as "you". You acce pt th e lice nse if you copy, m odify or distribute th e w ork in a w ay re q uiring pe rm ission unde r copyrigh t law . A "Modifie d Ve rsion" of th e D ocum e nt m e ans any w ork containing th e D ocum e nt or a portion of it, e ith e r copie d ve rbatim , or w ith m odifications and/or translate d into anoth e r language. A "Se condary Se ction" is a nam e d appe ndix or a front-m atte r se ction of th e D ocum e nt th at de als e xclusive ly w ith th e re lationsh ip of th e publish e rs or auth ors of th e D ocum e nt to th e D ocum e nt's ove rallsubje ct (or to re late d m atte rs)and contains noth ing th at could falldire ctly w ith in th at ove rallsubje ct. (Th us, if th e D ocum e nt is in part a te xtbook of m ath e m atics, a Se condary Se ction m ay not e xplain any m ath e m atics.) Th e re lationsh ip could be a m atte r of h istoricalconne ction w ith th e subje ct or w ith re late d m atte rs, or of legal,com m e rcial,ph ilosoph ical,e th ical or politicalposition re garding th e m . Th e "Invariant Se ctions" are ce rtain Se condary Se ctions w h ose titles are de signate d, as be ing th ose of Invariant Se ctions, in th e notice th at says th at th e D ocum e nt is re lease d unde r th is Lice nse. If a se ction doe s not fit th e above de finition of Se condary th e n it is not allow e d to be de signate d as Invariant. Th e D ocum e nt m ay contain ze ro
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