(?:`)?(?:nethack`general`public`license)?(?:`)?(?:.{,5000})`\(based`on`the`bison`general`public`license,`copyright`1988`richard`m\.`stallman\)`everyone`is`permitted`to`copy`and`distribute`verbatim`copies`of`this`license,`but`changing`it`is`not`allowed\.`you`can`also`use`this`wording`to`make`the`terms`for`other`programs\.`the`license`agreements`of`most`software`companies`keep`you`at`the`mercy`of`those`companies\.`by`contrast,`our`general`public`license`is`intended`to`give`everyone`the`right`to`share`nethack\.`to`make`sure`that`you`get`the`rights`we`want`you`to`have,`we`need`to`make`restrictions`that`forbid`anyone`to`deny`you`these`rights`or`to`ask`you`to`surrender`the`rights\.`hence`this`license`agreement\.`specifically,`we`want`to`make`sure`that`you`have`the`right`to`give`away`copies`of`nethack,`that`you`receive`source`code`or`else`can`get`it`if`you`want`it,`that`you`can`change`nethack`or`use`pieces`of`it`in`new`free`programs,`and`that`you`know`you`can`do`these`things\.`to`make`sure`that`everyone`has`such`rights,`we`have`to`forbid`you`to`deprive`anyone`else`of`these`rights\.`for`example,`if`you`distribute`copies`of`nethack,`you`must`give`the`recipients`all`the`rights`that`you`have\.`you`must`make`sure`that`they,`too,`receive`or`can`get`the`source`code\.`and`you`must`tell`them`their`rights\.`also,`for`our`own`protection,`we`must`make`certain`that`everyone`finds`out`that`there`is`no`warranty`for`nethack\.`if`nethack`is`modified`by`someone`else`and`passed`on,`we`want`its`recipients`to`know`that`what`they`have`is`not`what`we`distributed\.`therefore`we`\(mike`stephenson`and`other`holders`of`nethack`copyrights\)`make`the`following`terms`which`say`what`you`must`do`to`be`allowed`to`distribute`or`change`nethack\.`copying`policies`(?:.{,20})`you`may`copy`and`distribute`verbatim`copies`of`nethack`source`code`as`you`receive`it,`in`any`medium,`provided`that`you`keep`intact`the`notices`on`all`files`that`refer`to`copyrights,`to`this`license`agreement,`and`to`the`absence`of`any`warranty;`and`give`any`other`recipients`of`the`nethack`program`a`copy`of`this`license`agreement`along`with`the`program\.`(?:.{,20})`you`may`modify`your`copy`or`copies`of`nethack`or`any`portion`of`it,`and`copy`and`distribute`such`modifications`under`the`terms`of`paragraph`1`above`\(including`distributing`this`license`agreement\),`provided`that`you`also`do`the`following:`(?:.{,20})`cause`the`modified`files`to`carry`prominent`notices`stating`that`you`changed`the`files`and`the`date`of`any`change;`and`(?:.{,20})`cause`the`whole`of`any`work`that`you`distribute`or`publish,`that`in`whole`or`in`part`contains`or`is`a`derivative`of`nethack`or`any`part`thereof,`to`be`licensed`at`no`charge`to`all`third`parties`on`terms`identical`to`those`contained`in`this`license`agreement`\(except`that`you`may`choose`to`grant`more`extensive`warranty`protection`to`some`or`all`third`parties,`at`your`option\)`(?:.{,20})`you`may`charge`a`distribution`fee`for`the`physical`act`of`transferring`a`copy,`and`you`may`at`your`option`offer`warranty`protection`in`exchange`for`a`fee\.`(?:.{,20})`you`may`copy`and`distribute`nethack`\(or`a`portion`or`derivative`of`it,`under`paragraph`2\)`in`object`code`or`executable`form`under`the`terms`of`paragraphs`1`and`2`above`provided`that`you`also`do`one`of`the`following:`(?:.{,20})`accompany`it`with`the`complete`machine\-`readable`source`code,`which`must`be`distributed`under`the`terms`of`paragraphs`1`and`2`above;`or,`(?:.{,20})`accompany`it`with`full`information`as`to`how`to`obtain`the`complete`machine\-`readable`source`code`from`an`appropriate`archive`site\.`\(this`alternative`is`allowed`only`for`noncommercial`distribution\.\)`for`these`purposes,`complete`source`code`means`either`the`full`source`distribution`as`originally`released`over`usenet`or`updated`copies`of`the`files`in`this`distribution`used`to`create`the`object`code`or`executable\.`(?:.{,20})`you`may`not`copy,`sublicense,`distribute`or`transfer`nethack`except`as`expressly`provided`under`this`license`agreement\.`any`attempt`otherwise`to`copy,`sublicense,`distribute`or`transfer`nethack`is`void`and`your`rights`to`use`the`program`under`this`license`agreement`shall`be`automatically`terminated\.`however,`parties`who`have`received`computer`software`programs`from`you`with`this`license`agreement`will`not`have`their`licenses`terminated`so`long`as`such`parties`remain`in`full`compliance\.`stated`plainly:`you`are`permitted`to`modify`nethack,`or`otherwise`use`parts`of`nethack,`provided`that`you`comply`with`the`conditions`specified`above;`in`particular,`your`modified`nethack`or`program`containing`parts`of`nethack`must`remain`freely`available`as`provided`in`this`license`agreement\.`in`other`words,`go`ahead`and`share`nethack,`but`don`t`try`to`stop`anyone`else`from`sharing`it`farther\.