⭐ 欢迎来到虫虫下载站! | 📦 资源下载 📁 资源专辑 ℹ️ 关于我们
⭐ 虫虫下载站

📄 rfc1341.ps

📁 中、英文RFC文档大全打包下载完全版 .
💻 PS
📖 第 1 页 / 共 5 页
字号:
2154(aside)X2392(from)X2619(support)X2947(for)X3099(the)X3257(indicated)X3651(character)X4045(set.)X1296 3824(Subtypes)N1695(are)X1860(to)X1982(be)X2120(used)X2343(for)X2502(enriched)X2881(text)X3073(in)X3195(forms)X3466(where)X3747(application)X1296 3936(software)N1657(may)X1853(enhance)X2199(the)X2347(appearance)X2811(of)X2921(the)X3069(text,)X3268(but)X3421(such)X3627(software)X3989(must)X1296 4048(not)N1457(be)X1586(required)X1945(in)X2058(order)X2298(to)X2410(get)X2565(the)X2720(general)X3041(idea)X3239(of)X3356(the)X3511(content.)X3856(Possible)X1296 4160(subtypes)N1657(thus)X1842(include)X2151(any)X2 f2315(readable)X1 f2682(word)X2904(processor)X3297(format.)X3627(A)X3722(very)X3919(simple)X1296 4272(and)N1459(portable)X1799(subtype,)X2146(richtext,)X2489(is)X2577(de\256ned)X2884(in)X2983(this)X3146(document.)X3 f1008 4384(multipart)N1 f1441(--)X1543(data)X1742(consisting)X2170(of)X2289(multiple)X2650(parts)X2876(of)X2995(independent)X3505(data)X3705(types.)X3995(Four)X1296 4496(initial)N1580(subtypes)X1974(are)X2150(de\256ned,)X2515(including)X2937(the)X3113(primary)X3476("mixed")X3853(subtype,)X1296 4608("alternative")N1809(for)X1948(representing)X2451(the)X2596(same)X2821(data)X3009(in)X3112(multiple)X3462(formats,)X3808("parallel")X1296 4720(for)N1437(parts)X1653(intended)X2014(to)X2118(be)X2238(viewed)X2544(simultaneously,)X3179(and)X3346("digest")X3682(for)X3822(multipart)X1296 4832(entities)N1599(in)X1698(which)X1957(each)X2158(part)X2332(is)X2420(of)X2524(type)X2714("message".)X3 f1008 4944(message)N1 f1368(--)X1456(an)X1571(encapsulated)X2093(message.)X2491(A)X2584(body)X2800(of)X2905(Content-Type)X3465("message")X3894(is)X3983(itself)X1296 5056(a)N1380(fully)X1603(formatted)X2019(RFC)X2241(822)X2426(conformant)X2911(message)X3278(which)X3554(may)X3761(contain)X4085(its)X1296 5168(own)N1530(different)X1931(Content-Type)X2535(header)X2861(\256eld.)X3149(The)X3368(primary)X3743(subtype)X4112(is)X1296 5280("rfc822".)N1704(The)X1885("partial")X2241(subtype)X2571(is)X2666(de\256ned)X2980(for)X3123(partial)X3401(messages,)X3819(to)X3924(permit)X1296 5392(the)N1446(fragmented)X1917(transmission)X2435(of)X2547(bodies)X2831(that)X3009(are)X3160(thought)X3487(to)X3595(be)X3719(too)X3875(large)X4101(to)X1296 5504(be)N1425(passed)X1719(through)X2056(mail)X2266(transport)X2646(facilities.)X3065(Another)X3418(subtype,)X3778("External-)X1296 5616(body",)N1586(is)X1685(de\256ned)X2003(for)X2150(specifying)X2586(large)X2814(bodies)X3100(by)X3232(reference)X3627(to)X3738(an)X3865(external)X1296 5728(data)N1481(source.)X720 6160(Borenstein)N1161(&)X1260(Freed)X3853([Page)X4096(7])X8 p%%Page: 8 912 s 12 xH 0 xS 1 f3 f1 f720 400(RFC)N925(1341)X1545(MIME:)X1857(Multipurpose)X2399(Internet)X2723(Mail)X2929(Extensions)X3784(June)X3984(1992)X3 f1008 688(image)N1 f1301(--)X1437(image)X1721(data.)X1978(Image)X2267(requires)X2625(a)X2716(display)X3042(device)X3342(\(such)X3598(as)X3726(a)X3817(graphical)X1296 800(display,)N1641(a)X1727(printer,)X2051(or)X2174(a)X2260(FAX)X2493(machine\))X2894(to)X3011(view)X3240(the)X3400(information.)X3945(Initial)X1296 912(subtypes)N1656(are)X1798(de\256ned)X2105(for)X2241(two)X2409(widely-used)X2903(image)X3163(formats,)X3505(jpeg)X3695(and)X3858(gif.)X3 f1008 1024(audio)N1 f1264(--)X1379(audio)X1620(data,)X1832(with)X2030(initial)X2284(subtype)X2611("basic".)X2963(Audio)X3231(requires)X3569(an)X3688(audio)X3930(output)X1296 1136(device)N1572(\(such)X1804(as)X1908(a)X1975(speaker)X2293(or)X2397(a)X2464(telephone\))X2895(to)X2994("display")X3374(the)X3516(contents.)X3 f1008 1248(video)N1 f1267(--)X1396(video)X1651(data.)X1901(Video)X2177(requires)X2528(the)X2687(capability)X3109(to)X3225(display)X3544(moving)X3879(images,)X1296 1360(typically)N1659(including)X2048(specialized)X2502(hardware)X2885(and)X3049(software.)X3453(The)X3627(initial)X3877(subtype)X1296 1472(is)N1384("mpeg".)X3 f1008 1584(application)N1 f1496(--)X1590(some)X1823(other)X2051(kind)X2252(of)X2362(data,)X2577(typically)X2945(either)X3195(uninterpreted)X3739(binary)X4015(data)X1296 1696(or)N1407(information)X1893(to)X1999(be)X2121(processed)X2531(by)X2658(a)X2731(mail-based)X3184(application.)X3691(The)X3871(primary)X1296 1808(subtype,)N1652("octet-stream",)X2265(is)X2363(to)X2472(be)X2597(used)X2807(in)X2916(the)X3068(case)X3268(of)X3382(uninterpreted)X3930(binary)X1296 1920(data,)N1515(in)X1624(which)X1893(case)X2092(the)X2243(simplest)X2597(recommended)X3176(action)X3445(is)X3542(to)X3650(offer)X3870(to)X3978(write)X1296 2032(the)N1447(information)X1935(into)X2118(a)X2194(\256le)X2351(for)X2497(the)X2649(user.)X2867(Two)X3077(additional)X3497(subtypes,)X3891("ODA")X1296 2144(and)N1501("PostScript",)X2064(are)X2248(de\256ned)X2597(for)X2775(transporting)X3305(ODA)X3577(and)X3781(PostScript)X1296 2256(documents)N1770(in)X1902(bodies.)X2258(Other)X2534(expected)X2934(uses)X3157(for)X3327("application")X3892(include)X1296 2368(spreadsheets,)N1843(data)X2041(for)X2190(mail-based)X2650(scheduling)X3104(systems,)X3468(and)X3643(languages)X4064(for)X1296 2480("active")N1649(\(computational\))X2309(email.)X2616(\(Note)X2880(that)X3070(active)X3346(email)X3606(entails)X3903(several)X1296 2592(securityconsiderations,)N2270(which)X2594(are)X2801(discussed)X3258(later)X3519(in)X3683(this)X3911(memo,)X1296 2704(particularly)N1765(in)X1864(the)X2006(context)X2314(of)X2418(application/PostScript.\))X720 2928(Default)N1050(RFC)X1272(822)X1457(messages)X1861(are)X2020(typed)X2275(by)X2412(this)X2592(protocol)X2954(as)X3075(plain)X3309(text)X3495(in)X3612(the)X3772(US-ASCII)X720 3040(character)N1104(set,)X1265(which)X1530(can)X1694(be)X1815(explicitly)X2209(speci\256ed)X2580(as)X2689("Content-type:)X3311(text/plain;)X3732(charset=us-)X720 3152(ascii".)N999(If)X1102(no)X1237(Content-Type)X1811(is)X1914(speci\256ed,)X2319(either)X2578(by)X2713(error)X2939(or)X3059(by)X3195(an)X3326(older)X3564(user)X3764(agent,)X4037(this)X720 3264(default)N1022(is)X1120(assumed.)X1556(In)X1669(the)X1820(presence)X2190(of)X2303(a)X2379(MIME-Version)X3009(header)X3299(\256eld,)X3527(a)X3603(receiving)X3995(User)X720 3376(Agent)N983(can)X1145(also)X1329(assume)X1641(that)X1815(plain)X2037(US-ASCII)X2470(text)X2644(was)X2822(the)X2969(sender's)X3318(intent.)X3615(In)X3724(the)X3871(absence)X720 3488(of)N839(a)X921(MIME-Version)X1557(speci\256cation,)X2107(plain)X2339(US-ASCII)X2782(text)X2966(must)X3192(still)X3375(be)X3504(assumed,)X3897(but)X4058(the)X720 3600(sender's)N1064(intent)X1308(might)X1557(have)X1763(been)X1969(otherwise.)X720 3824(RATIONALE:)N1369(In)X1498(the)X1665(absence)X2019(of)X2148(any)X2336(Content-Type)X2921(header)X3228(\256eld)X3449(or)X3579(MIME-Version)X720 3936(header)N1003(\256eld,)X1224(it)X1304(is)X1394(impossible)X1837(to)X1938(be)X2055(certain)X2344(that)X2515(a)X2584(message)X2936(is)X3026(actually)X3358(text)X3529(in)X3629(the)X3772(US-ASCII)X720 4048(character)N1108(set,)X1273(since)X1505(it)X1593(might)X1852(well)X2052(be)X2177(a)X2254(message)X2614(that,)X2817(using)X3059(the)X3212(conventions)X3712(that)X3892(predate)X720 4160(this)N887(document,)X1319(includes)X1668(text)X1841(in)X1944(another)X2261(character)X2643(set)X2778(or)X2886(non-textual)X3353(data)X3542(in)X3645(a)X3715(manner)X4031(that)X720 4272(cannot)N1030(be)X1174 0.2812(automatically)AX1753(recognized)X2229(\(e.g.,)X2477(a)X2573(uuencoded)X3043(compressed)X3550(UNIX)X3842(tar)X3997(\256le\).)X720 4384(Although)N1120(there)X1350(is)X1451(no)X1584(fully)X1803(acceptable)X2248(alternative)X2693(to)X2805(treating)X3137(such)X3350(untyped)X3697(messages)X4096(as)X720 4496("text/plain;)N1179(charset=us-ascii",)X1891(implementors)X2449(should)X2733(remain)X3030(aware)X3289(that)X3463(if)X3551(a)X3623(message)X3978(lacks)X720 4608(both)N925(the)X1077(MIME-Version)X1708(and)X1881(the)X2033(Content-Type)X2602(header)X2893(\256elds,)X3159(it)X3246(may)X3445(in)X3553(practice)X3892(contain)X720 4720(almost)N1001(anything.)X720 4944(It)N809(should)X1095(be)X1216(noted)X1460(that)X1635(the)X1783(list)X1932(of)X2043(Content-Type)X2609(values)X2886(given)X3131(here)X3328(may)X3525(be)X3647(augmented)X4101(in)X720 5056(time,)N953(via)X1108(the)X1263(mechanisms)X1776(described)X2182(above,)X2473(and)X2649(that)X2831(the)X2986(set)X3130(of)X3247(subtypes)X3620(is)X3721(expected)X4101(to)X720 5168(grow)N941(substantially.)X720 5392(When)N993(a)X1079(mail)X1294(reader)X1578(encounters)X2038(mail)X2253(with)X2467(an)X2601(unknown)X3001(Content-type)X3547(value,)X3823(it)X3920(should)X720 5504(generally)N1120(treat)X1333(it)X1428(as)X1549(equivalent)X1991(to)X2106 0.1851("application/octet-stream",)AX3181(as)X3301(described)X3710(later)X3922(in)X4037(this)X720 5616(document.)N720 6160(Borenstein)N1161(&)X1260(Freed)X3853([Page)X4096(8])X9 p%%Page: 9 1012 s 12 xH 0 xS 1 f720 400(RFC)N925(1341)X1545(MIME:)X1857(Multipurpose)X2399(Internet)X2723(Mail)X2929(Extensions)X3784(June)X3984(1992)X3 f14 s720 704(5)N1008(The)X1222(Content-Transfer-Encoding)X2590(Header)X2973(Field)X1 f12 s720 960(Many)N978(Content-Types)X1584(which)X1854(could)X2103(usefully)X2448(be)X2574(transported)X3042(via)X3195(email)X3445(are)X3598(represented,)X4101(in)X720 1072(their)N926("natural")X1301(format,)X1610(as)X1718(8-bit)X1928(character)X2310(or)X2418(binary)X2692(data.)X2929(Such)X3149(data)X3338(cannot)X3623(be)X3742(transmitted)X720 1184(over)N926(some)X1164(transport)X1541(protocols.)X1982(For)X2151(example,)X2538(RFC)X2755(821)X2935(restricts)X3276(mail)X3484(messages)X3883(to)X3994(7-bit)X720 1296(US-ASCII)N1148(data)X1333(with)X1528(1000)X1744(character)X2122(lines.)X720 1520(It)N803(is)X891(necessary,)X1313(therefore,)X1709(to)X1808(de\256ne)X2067(a)X2134(standard)X2485(mechanism)X2949(for)X3086(re-encoding)X3571(such)X3772(data)X3958(into)X4133(a)X720 1632(7-bit)N929(short-line)X1325(format.)X1657(This)X1855(document)X2261(speci\256es)X2618(that)X2789(such)X2991(encodings)X3407(will)X3583(be)X3700(indicated)X4080(by)X720 1744(a)N798(new)X993("Content-Transfer-Encoding")X2171(header)X2464(\256eld.)X2719(The)X2905 0.1276(Content-Transfer-Encoding)AX4005(\256eld)X720 1856(is)N813(used)X1017(to)X1120(indicate)X1454(the)X1600(type)X1794(of)X1902(transformation)X2497(that)X2670(has)X2826(been)X3036(used)X3240(in)X3343(order)X3574(to)X3677(represent)X4058(the)X720 1968(body)N936(in)X1035(an)X1150(acceptable)X1582(manner)X1895(for)X2031(transport.)X720 2192(Unlike)N1070(Content-Types,)X1754(a)X1885(proliferation)X2455(of)X2624 0.1276(Content-Transfer-Encoding)AX3777(values)X4112(is)X720 2304(undesirable)N1212(and)X1399(unnecessary.)X1965(However,)X2389(establishing)X2896(only)X3114(a)X3204(single)X3481(Content-Transfer-)X720 2416(Encoding)N1115(mechanism)X1580(does)X1782(not)X1931(seem)X2155(possible.)X2569(There)X2821(is)X2912(a)X2982(tradeoff)X3314(between)X3662(the)X3807(desire)X4064(for)X720 2528(a)N804(compact)X1172(and)X1351(ef\256cient)X1707(encoding)X2100(of)X2220(largely-binary)X2806(data)X3007(and)X3186(the)X3344(desire)X3614(for)X3766(a)X3849(readable)X720 2640(encoding)N1102(of)X1211(data)X1401(that)X1575(is)X1668(mostly,)X1983(but)X2135(not)X2288(entirely,)X2637(7-bit)X2849(data.)X3088(For)X3251(this)X3420(reason,)X3725(at)X3825(

⌨️ 快捷键说明

复制代码 Ctrl + C
搜索代码 Ctrl + F
全屏模式 F11
切换主题 Ctrl + Shift + D
显示快捷键 ?
增大字号 Ctrl + =
减小字号 Ctrl + -