Users Guide

Fi nal l y, any f r ee pr ogr am i s t hr eat ened const ant l y by sof t war e pat ent s. We wi sh t o avoi d t he danger t hat
r edi st r i but or s of a f r ee pr ogr am wi l l i ndi vi dual l y obt ai n pat ent l i censes, i n ef f ect maki ng t he pr ogr am
pr opr i et ar y. To pr event t hi s, we have made i t cl ear t hat any pat ent must be l i censed f or ever yone' s f r ee use
or not l i censed at al l .
The pr eci se t er ms and condi t i ons f or copyi ng, di st r i but i on and modi f i cat i on f ol l ow.
GNU GENERAL PUBLI C LI CENSE
TERMS AND CONDI TI ONS FOR COPYI NG, DI STRI BUTI ON AND MODI FI CATI ON
0. Thi s Li cense appl i es t o any pr ogr am or ot her wor k whi ch cont ai ns a not i ce pl aced by t he copyr i ght hol der
sayi ng i t may be di st r i but ed under t he t er ms of t hi s Gener al Publ i c Li cense. The " Pr ogr am", bel ow, r ef er s t o
any such pr ogr am or wor k, and a " wor k based on t he Pr ogr am" means ei t her t he Pr ogr am or any der i vat i ve wor k
under copyr i ght l aw: t hat i s t o say, a wor k cont ai ni ng t he Pr ogr am or a por t i on of i t , ei t her ver bat i m or
wi t h modi f i cat i ons and/ or t r ansl at ed i nt o anot her l anguage. ( Her ei naf t er , t ransl at i on i s i ncl uded wi t hout
l i mi t at i on i n t he t er m " modi f i cat i on" . ) Each l i censee i s addr essed as " you" . Act i vi t i es ot her t han copyi ng,
di st r i but i on and modi f i cat i on ar e not cover ed by t hi s Li cense; t hey ar e out si de i t s scope. The act of r unni ng
t he Pr ogr am i s not r est r i ct ed, and t he out put f r om t he Pr ogr am i s cover ed onl y i f i t s cont ent s const i t ut e a
wor k based on t he Pr ogr am ( i ndependent of havi ng been made by r unni ng t he Pr ogr am) . Whet her t hat i s t r ue
depends on what t he Pr ogr am does.
1. You may copy and di st r i but e ver bat i m copi es of t he Pr ogr am' s sour ce code as you r ecei ve i t , i n any medi um,
pr ovi ded t hat you conspi cuousl y and appr opr i at el y publ i sh on each copy an appr opr i at e copyr i ght not i ce and
di scl ai mer of war r ant y; keep i nt act al l t he not i ces t hat r ef er t o t hi s Li cense and t o t he absence of any
war rant y; and gi ve any ot her reci pi ent s of t he Pr ogr am a copy of t hi s Li cense al ong wi t h t he Pr ogr am.
You may char ge a f ee f or t he physi cal act of t r ansf er ri ng a copy, and you may at your opt i on of f er war rant y
pr ot ect i on i n exchange f or a f ee.
2. You may modi f y your copy or copi es of t he Pr ogr am or any por t i on of i t , t hus f or mi ng a wor k based on t he
Pr ogr am, and copy and di st r i but e such modi f i cat i ons or wor k under t he t er ms of Sect i on 1 above, pr ovi ded t hat
you al so meet al l of t hese condi t i ons:
a. You must cause t he modi f i ed f i l es t o car r y pr omi nent not i ces st at i ng t hat you changed t he f i l es and t he
dat e of any change.
b. You must cause any wor k t hat you di st r i but e or publ i sh, t hat i n whol e or i n par t cont ai ns or i s der i ved
f r om t he Pr ogr am or any par t t her eof , t o be l i censed as a whol e at no char ge t o al l t hi r d par t i es under t he
t er ms of t hi s Li cense.
c. I f t he modi f i ed pr ogr am nor mal l y r eads commands i nt er act i vel y when r un, you must cause i t , when st ar t ed
r unni ng f or such i nt er act i ve use i n t he most or di nar y way, t o pr i nt or di spl ay an announcement i ncl udi ng an
appr opr i at e copyr i ght not i ce and a not i ce t hat t her e i s no war r ant y ( or el se, sayi ng t hat you pr ovi de a
war rant y) and t hat user s may r edi st r i but e t he pr ogr am under t hese condi t i ons, and t el l i ng t he user how t o
vi ew a copy of t hi s Li cense. ( Except i on: i f t he Progr am i t sel f i s i nt er act i ve but does not nor mal l y pr i nt
such an announcement , your wor k based on t he Pr ogr am i s not r equi r ed t o pr i nt an announcement . )
These r equi r ement s appl y t o t he modi f i ed wor k as a whol e. I f i dent i f i abl e sect i ons of t hat wor k ar e not
der i ved f r om t he Pr ogr am, and can be r easonabl y consi der ed i ndependent and separ at e wor ks i n t hemsel ves, t hen
t hi s Li cense, and i t s t er ms, do not appl y t o t hose sect i ons when you di st r i but e t hem as separ at e wor ks. But
when you di st r i but e t he same sect i ons as par t of a whol e whi ch i s a wor k based on t he Pr ogr am, t he
di st r i but i on of t he whol e must be on t he t er ms of t hi s Li cense, whose per mi ssi ons f or ot her l i censees ext end
t o t he ent i r e whol e, and t hus t o each and ever y par t r egar dl ess of who wr ot e i t .
Thus, i t i s not t he i nt ent of t hi s sect i on t o cl ai m r i ght s or cont est your r i ght s t o wor k wr i t t en ent i r el y by
you; r at her , t he i nt ent i s t o exer ci se t he r i ght t o cont r ol t he di st r i but i on of der i vat i ve or col l ect i ve
wor ks based on t he Progr am.