| Giʼiz | gez-001 | X3L" |
| Bilen | byn-002 | X3l |
| myxʼabišdy čʼel | rut-000 | X3l |
| Lushootseed Skagit | lut-000 | x3L" |
| Sechelt | sec-000 | x3L" |
| Mbizinaku | bkm-001 | x3l |
| Nxaảmxcín | col-000 | x3l |
| Tacheng Dagur | dta-001 | x3l |
| ASCII Upriver Halkomelem | hur-004 | x3l |
| Khanty | kca-017 | x3l |
| Tacheng Dagur | dta-001 | x3l3g |
| Nooksack | nok-000 | x3L"3n |
| Diegueno | dih-001 | x3La |
| Kpɛlɛwoo | xpe-000 | x3la |
| Nxaảmxcín | col-000 | X3laxw~ |
| Diegueno | dih-001 | x3LC3puk |
| Qafár af | aar-000 | X3lE |
| Korowai | khe-000 | x3le |
| Rendille | rel-000 | X3lEsi |
| Toga | lht-000 | x3litpi3 |
| Nxaảmxcín | col-000 | X3lq"3n |
| Diegueno | dih-001 | x3Lta |
| Diegueno | dih-001 | x3Lty~ta |
| Glavda | glw-000 | x3luwa |
| lygʼoravetlʼen jilǝjil | ckt-001 | x3Lx3n |
| Alyutor | alr-000 | x3lx3n |
| Nymylan | kpy-000 | x3lx3n |
| чӑваш | chv-000 | x3lxa |
| Tsakhur | tkr-000 | X3ly~ |
| Nxaảmxcín | col-000 | X3m" |
| lygʼoravetlʼen jilǝjil | ckt-001 | x3m |
| Shuiqing Sui | swi-002 | x3m |
| Diegueno | dih-001 | x3m3tun |
| Diegueno | dih-001 | x3maL |
| arevelahayeren | hye-002 | x3me |
| hyw-001 | x3me | |
| Au | avt-000 | x3mik |
| Diegueno | dih-001 | x3miy |
| North Itelmen | itl-001 | x3mLX |
| South Itelmen | itl-002 | x3mLx |
| Alyutor | alr-000 | x3mm3 |
| Nymylan | kpy-000 | x3mmo |
| Hongfeng Gelao | aou-001 | %x3n |
| Giʼiz | gez-001 | X3n |
| Tigré | tig-001 | X3n |
| Lamet | lbn-000 | x3N |
| Taungthu | blk-001 | x3n |
| Dongying Lingao | onb-002 | x3n |
| Tai2 Lə6 | tdd-001 | x3n |
| Tera | ttr-000 | x3n |
| Thai Trang | twh-000 | x3n |
| Wuming | zyb-001 | x3n |
| Duhtu Tsou | tsu-001 | x3N3 |
| nəxʷsƛ̕ay̕əmúcən | clm-000 | X3n7axw~ |
| المغربية | ary-000 | X3na |
| Tigré | tig-001 | X3na |
| Syriac | syc-001 | X3nan |
| Sliammon | coo-001 | x3nat |
| Boga | bvw-000 | x3nd~3ra7a |
| Korowai | khe-000 | x3nd~ep |
| Kamwe—Higi Futu | hig-001 | x3ni |
| Kota Agung Lampung Api | ljp-005 | X3Nloyo |
| Even | eve-001 | X3nN3n |
| Boga | bvw-000 | x3nNgw$iya |
| tigrinya | tir-003 | X3ns"3ti |
| Ranau Lampung Api | ljp-008 | x3Nx3N |
| Kayu Agung Asli Komering | kge-003 | X3NXoye |
| Quinault | qun-000 | X3p |
| Barbareño | boi-000 | x3p |
| Samala | inz-000 | x3p |
| Kobon | kpw-000 | x3p |
| Ventureño | veo-000 | x3p |
| Diegueno | dih-001 | x3p3Siw |
| Cowlitz | cow-000 | X3pL |
| Qʼwayʼayiłqʼ | cjh-000 | X3pmL |
| Lalo | ywt-001 | x3q |
| Proto-Malayo-Polynesian | poz-000 | *X₃ + qatay |
| лезги чӀал | lez-000 | X3r |
| Au | avt-000 | x3r |
| Yidgha | ydg-000 | x3r |
| Nanaj | gld-000 | x3r3kt3 |
| Orok | oaa-000 | x3r3kt3 |
| Olcha | ulc-000 | x3r3kt3 |
| English | eng-000 | X3: Reunion |
| français | fra-000 | X3: Reunion |
| italiano | ita-000 | X3: Reunion |
| polski | pol-000 | X3: Reunion |
| русский | rus-000 | X3: Reunion |
| Nanaj | gld-000 | x3rN3n |
| nǚzhēn | juc-000 | x3rN3n |
| Ningil | niz-000 | x3roi |
| Boikin—Pogo-Rawo | bzf-002 | x3ryk |
| Boikin—Pogo-Rawo | bzf-002 | x3rykN |
| Ghadamès | gha-000 | x3s |
| Jerba | jbn-000 | x3s |
| Khanty | kca-017 | x3s |
| Larevat | lrv-000 | x3s |
| Maragus | mrs-000 | x3s |
| Babessi | bse-000 | x3s3k3 |
| Giʼiz | gez-001 | X3s"E |
| Ura | uur-000 | x3si |
| Kamwe—Higi Futu | hig-001 | x3Sini |
| Ṣurayt | tru-001 | x3Smo |
| Nxaảmxcín | col-000 | X3st |
| English | eng-000 | X-3 Stiletto |
| Türkçe | tur-000 | X-3 Stiletto |
| magyar | hun-000 | X–3 Stiletto |
| Bulu | bum-000 | x3t |
| lygʼoravetlʼen jilǝjil | ckt-001 | x3t |
| Maragus | mrs-000 | x3t |
| Leviamp | nmb-001 | x3t |
| Unmet | nmb-002 | x3t |
| koʼrevajù chùʼo | coe-000 | x3*t3 |
| Orejón | ore-000 | x3t3 |
| Cineni | cie-000 | x3t3ra |
| Chru | cje-000 | x3tai |
| Diegueno | dih-001 | x3tat |
| English | eng-000 | X3 Technology Pressure Imaging Software file |
| Jino | jiu-000 | x3 th~a |
| Jino | jiu-000 | x3th~a |
| Sisiqa | baa-004 | x3ti |
| Alyutor | alr-000 | x3tkalN3n |
| Nymylan | kpy-000 | x3tkalN3n |
| lygʼoravetlʼen jilǝjil | ckt-001 | x3tkaLx3n |
| Ranau Lampung Api | ljp-008 | x3toN |
| Judeo Tat | jdt-000 | X3toS |
| Alyutor | alr-000 | x3tt3 |
| Alyutor | alr-000 | X3tX3m |
| Nymylan | kpy-000 | X3tX3m |
| Alyutor | alr-000 | x3tx3n |
| Mazhelong Bai | bfs-002 | x3u |
| Dagur | dta-000 | x3ur |
| Proto-Chukotko-Kamchatkan | ckt-002 | x3v |
| Proto-Chukotko-Kamchatkan | ckt-002 | x3vx3v |
| Carolinian | cal-000 | x3w |
| Moresada | msx-000 | x3w3Nk |
| nəxʷsƛ̕ay̕əmúcən | clm-000 | X3w"3s |
| Salish Straits | str-001 | X3w3s |
| SENĆOŦEN | str-002 | x3w"3s |
| Nooksack | nok-000 | x3w3s |
| Osum | omo-000 | x3wa |
| Diegueno | dih-001 | x3wak |
| Sliammon | coo-001 | x3wSin |
| Ranau Lampung Api | ljp-008 | x3x |
| Carolinian | cal-000 | x3x3 |
| Hulʼqʼumiʼnumʼ | hur-001 | X3X3k"w~3m |
| Samish | str-003 | X3Xak"w~ |
| Burmbar Vartavo | vrt-002 | x3xut |
| Kilba | hbb-000 | x3ya |
| Diegueno | dih-001 | x3yuL |
| Mehri | gdq-000 | X3yum |
| Saho | ssy-000 | X3z3 |
| Daba | dbq-000 | x3za |
| المغربية | ary-000 | X3Zra |
| Glavda | glw-000 | x3zuwa |
| 國語 | cmn-001 | X3列車 |
| 國語 | cmn-001 | X-3試驗機 |
| polski | pol-000 | X-4 |
| magyar | hun-000 | X–4 |
| filename extensions | art-335 | x40 |
| 普通话 | cmn-000 | X. 400 |
| العربية | arb-000 | X.400 |
| bălgarski ezik | bul-001 | X.400 |
| català | cat-000 | X.400 |
| 普通话 | cmn-000 | X.400 |
| dansk | dan-000 | X.400 |
| Deutsch | deu-000 | X.400 |
| eesti | ekk-000 | X.400 |
| ελληνικά | ell-000 | X.400 |
| English | eng-000 | X.400 |
| euskara | eus-000 | X.400 |
| suomi | fin-000 | X.400 |
| français | fra-000 | X.400 |
| galego | glg-000 | X.400 |
| עברית | heb-000 | X.400 |
| hrvatski | hrv-000 | X.400 |
| magyar | hun-000 | X.400 |
| bahasa Indonesia | ind-000 | X.400 |
| íslenska | isl-000 | X.400 |
| italiano | ita-000 | X.400 |
| 日本語 | jpn-000 | X.400 |
| Qazaq tili | kaz-002 | X.400 |
| Hangungmal | kor-001 | X.400 |
| lietuvių | lit-000 | X.400 |
| latviešu | lvs-000 | X.400 |
| Nederlands | nld-000 | X.400 |
| bokmål | nob-000 | X.400 |
| فارسی | pes-000 | X.400 |
| polski | pol-000 | X.400 |
| português | por-000 | X.400 |
| română | ron-000 | X.400 |
| русский | rus-000 | X.400 |
| slovenčina | slk-000 | X.400 |
| slovenščina | slv-000 | X.400 |
| español | spa-000 | X.400 |
| srpski | srp-001 | X.400 |
| svenska | swe-000 | X.400 |
| Tagalog | tgl-000 | X.400 |
| ภาษาไทย | tha-000 | X.400 |
| Türkçe | tur-000 | X.400 |
| українська | ukr-000 | X.400 |
| اردو | urd-000 | X.400 |
| tiếng Việt | vie-000 | X.400 |
| Bahasa Malaysia | zsm-000 | X.400 |
| English | eng-000 | X.400 Address |
| Türkçe | tur-000 | X.400 Adresi |
| English | eng-000 | X.400 recommendation |
| English | eng-000 | X.400 system |
| TechTarget file types | art-336 | X40-Xtree-gold-Dos-help-file |
| Deutsch | deu-000 | X-41 Common Aero Vehicle |
| English | eng-000 | X-41 Common Aero Vehicle |
| français | fra-000 | X 4200 |
| Deutsch | deu-000 | X-42 Pop-Up Upper Stage |
| English | eng-000 | X-42 Pop-Up Upper Stage |
| 日本語 | jpn-000 | X-43 |
| magyar | hun-000 | X–43 |
| Esperanto | epo-000 | X-43A |
| 國語 | cmn-001 | X-43A試驗機 |
| français | fra-000 | X-43 Scramjet |
| English | eng-000 | X-44 MANTA |
| 國語 | cmn-001 | X-44試驗機 |
| français | fra-000 | X-45 |
| 日本語 | jpn-000 | X-45 |
| français | fra-000 | X-46 |
| 日本語 | jpn-000 | X-47 |
| English | eng-000 | X-47 Pegasus |
| français | fra-000 | X-47 Pegasus |
| lietuvių | lit-000 | X-47 Pegasus |
| 國語 | cmn-001 | X-49試驗機 |
| English | eng-000 | X-4 Bantam |
| suomi | fin-000 | X-4 Bantam |
| Türkçe | tur-000 | X-4 Bantam |
| magyar | hun-000 | X–4 Bantam |
| filename extensions | art-335 | x4k |
| Proto-Malayo-Polynesian | poz-000 | *X₄ + qatay |
| 國語 | cmn-001 | X-4試驗機 |
| 日本語 | jpn-000 | X-5 |
| magyar | hun-000 | X–5 |
| filename extensions | art-335 | x5 |
| filename extensions | art-335 | x50 |
| dansk | dan-000 | X.500 |
| Deutsch | deu-000 | X.500 |
| English | eng-000 | X.500 |
| français | fra-000 | X.500 |
| italiano | ita-000 | X.500 |
| 日本語 | jpn-000 | X.500 |
| Hangungmal | kor-001 | X.500 |
| Nederlands | nld-000 | X.500 |
| polski | pol-000 | X.500 |
| русский | rus-000 | X.500 |
| español | spa-000 | X.500 |
| Türkçe | tur-000 | X.500 Nesne Kimliği |
| English | eng-000 | X.500 OID |
| English | eng-000 | X.500 recommendation |
| Deutsch | deu-000 | X.509 |
| English | eng-000 | X.509 |
| français | fra-000 | X.509 |
| italiano | ita-000 | X.509 |
| 日本語 | jpn-000 | X.509 |
| Hangungmal | kor-001 | X.509 |
| polski | pol-000 | X.509 |
| português | por-000 | X.509 |
| español | spa-000 | X.509 |
| svenska | swe-000 | X.509 |
| tiếng Việt | vie-000 | X.509 |
| Nederlands | nld-000 | X.509-certicicaat |
| English | eng-000 | X.509 certificate |
| dansk | dan-000 | X.509-certifikat |
| svenska | swe-000 | X.509-certifikat |
| suomi | fin-000 | X.509-sertifikaatti |
| Türkçe | tur-000 | X.509 sertifikası |
| nynorsk | nno-000 | X.509-sertifikat |
| bokmål | nob-000 | X.509-sertifikat |
| magyar | hun-000 | X.509-tanúsítvány |
| Nederlands | nld-000 | X.509v3-certificaat |
| English | eng-000 | X.509 v3 certificate |
| dansk | dan-000 | X.509 v3-certifikat |
| svenska | swe-000 | X.509 v3-certifikat |
| bokmål | nob-000 | X.509 v3-sertifikat |
| magyar | hun-000 | X.509 v3 tanúsítvány |
| 한국어 | kor-000 | X.509 v3 인증서 |
| 國語 | cmn-001 | X.509 v3 憑證 |
| 日本語 | jpn-000 | X.509 v3 証明書 |
| 普通话 | cmn-000 | X.509 v3 证书 |
| Deutsch | deu-000 | X.509-Zertifikat |
| 한국어 | kor-000 | X.509 인증서 |
| 普通话 | cmn-000 | X.509 憑證 |
| TechTarget file types | art-336 | X50-Xtree-gold-Dos-help-file |
| 日本語 | jpn-000 | X-51 |
| русский | rus-000 | X-51A |
| English | eng-000 | X-53 Active Aeroelastic Wing |
| slovenščina | slv-000 | X-53 Active Aeroelastic Wing |
| Proto-Malayo-Polynesian | poz-000 | *X₅ + qatay |
| TechTarget file types | art-336 | X5-Rockwell-Software-Logix-5-File |
| 國語 | cmn-001 | X-5試驗機 |
| 日本語 | jpn-000 | X-6 |
| magyar | hun-000 | X–6 |
| svenska | swe-000 | X60 |
| filename extensions | art-335 | x60 |