| filename extensions | art-335 | x06 |
| TechTarget file types | art-336 | X06-Secondary-index-file-Paradox |
| filename extensions | art-335 | x07 |
| TechTarget file types | art-336 | X07-Secondary-index-file-Paradox |
| filename extensions | art-335 | x08 |
| TechTarget file types | art-336 | X08-Secondary-index-file-Paradox |
| filename extensions | art-335 | x09 |
| TechTarget file types | art-336 | X09-Secondary-index-file-Paradox |
| Deutsch | deu-000 | X-1 |
| suomi | fin-000 | X-1 |
| 日本語 | jpn-000 | X-1 |
| Nederlands | nld-000 | X-1 |
| 日本語 | jpn-000 | X1 |
| magyar | hun-000 | X–1 |
| filename extensions | art-335 | x1 |
| עברית | heb-000 | X-10 |
| català | cat-000 | X10 |
| Deutsch | deu-000 | X10 |
| English | eng-000 | X10 |
| suomi | fin-000 | X10 |
| français | fra-000 | X10 |
| 日本語 | jpn-000 | X10 |
| Nederlands | nld-000 | X10 |
| русский | rus-000 | X10 |
| español | spa-000 | X10 |
| filename extensions | art-335 | x10 |
| TechTarget file types | art-336 | X10-Bitmap-image-X-Window-dump |
| English | eng-000 | X-10 Graphite Reactor |
| TechTarget file types | art-336 | X10-X-Window-Dump-Bitmap |
| 日本語 | jpn-000 | X-11 |
| SPDX License List Identifier | art-298 | X11 |
| filename extensions | art-335 | x11 |
| English | eng-000 | X/1106 C1 |
| polski | pol-000 | X/1106 C1 |
| English | eng-000 | X11.app |
| English | eng-000 | X11 Bitmap |
| English | eng-000 | X11 Bitmap Graphic |
| TechTarget file types | art-336 | X11-Bitmap-image-X-Windows-system-window-dump |
| English | eng-000 | X11 License |
| English | eng-000 | X11 Pixmap Graphic |
| English | eng-000 | X11 Puzzle Bitmap |
| English | eng-000 | X11 Puzzle : Bitmap graphics |
| English | eng-000 | X11 Xim Toolkit Bitmap |
| English | eng-000 | X11 Xim Toolkit bitmap file |
| TechTarget file types | art-336 | X11-X-Windows-System-Window-Dump-Bitmap |
| 日本語 | jpn-000 | X-12 |
| English | eng-000 | X.121 |
| français | fra-000 | X.121 |
| English | eng-000 | X.121address |
| Türkçe | tur-000 | X.121adresi |
| English | eng-000 | X128 Spectrum emulator file |
| Deutsch | deu-000 | X-12-ARIMA |
| English | eng-000 | X-12-ARIMA |
| svenska | swe-000 | X-12-ARIMA |
| 日本語 | jpn-000 | X-13 |
| English | eng-000 | X-13 Vertijet |
| עברית | heb-000 | X-13 ורטיג׳ט |
| bălgarski ezik | bul-001 | X-15 |
| suomi | fin-000 | X-15 |
| עברית | heb-000 | X-15 |
| 日本語 | jpn-000 | X-15 |
| Nederlands | nld-000 | X-15 |
| português | por-000 | X-15 |
| magyar | hun-000 | X–15 |
| Türkçe | tur-000 | X -15 A |
| 國語 | cmn-001 | X-15試驗機 |
| 日本語 | jpn-000 | X-16 |
| filename extensions | art-335 | x16 |
| TechTarget file types | art-336 | X16-Macromedia-Extra-program-extension-16-bit |
| 日本語 | jpn-000 | X-17 |
| 日本語 | jpn-000 | X-18 |
| English | eng-000 | X1 Desktop Search Saved Search File |
| Proto-Malayo-Polynesian | poz-000 | *X₁ + qatay |
| English | eng-000 | X-1 Submarine |
| English | eng-000 | X1-theory |
| TechTarget file types | art-336 | X1-X1-Desktop-Search-Saved-Search-File-X1-Technologies-Inc |
| 日本語 | jpn-000 | Ｘ１理論 |
| 國語 | cmn-001 | X-1試驗機 |
| 日本語 | jpn-000 | X-2 |
| toskërishte | als-000 | X2 |
| Deutsch | deu-000 | X2 |
| English | eng-000 | X2 |
| italiano | ita-000 | X2 |
| Nederlands | nld-000 | X2 |
| português | por-000 | X2 |
| English | eng-000 | X² |
| 日本語 | jpn-000 | X-20 |
| filename extensions | art-335 | x20 |
| English | eng-000 | X-20 Dyna-Soar |
| français | fra-000 | X-20 Dyna-Soar |
| bokmål | nob-000 | X-20 Dyna-Soar |
| español | spa-000 | X-20 Dyna-Soar |
| TechTarget file types | art-336 | X20-XTree-Gold-DOS-Help-File |
| 國語 | cmn-001 | X-20試驗機 |
| 日本語 | jpn-000 | X-21 |
| Deutsch | deu-000 | X.21 |
| English | eng-000 | X.21 |
| français | fra-000 | X.21 |
| italiano | ita-000 | X.21 |
| dansk | dan-000 | X-23 |
| English | eng-000 | X-23 |
| français | fra-000 | X-23 |
| italiano | ita-000 | X-23 |
| Nederlands | nld-000 | X-23 |
| português | por-000 | X-23 |
| español | spa-000 | X-23 |
| English | eng-000 | X-23 PRIME |
| magyar | hun-000 | X–24 |
| 普通话 | cmn-000 | X-24试验机 |
| bosanski | bos-000 | X.25 |
| čeština | ces-000 | X.25 |
| 普通话 | cmn-000 | X.25 |
| 國語 | cmn-001 | X.25 |
| dansk | dan-000 | X.25 |
| Deutsch | deu-000 | X.25 |
| English | eng-000 | X.25 |
| euskara | eus-000 | X.25 |
| français | fra-000 | X.25 |
| italiano | ita-000 | X.25 |
| 日本語 | jpn-000 | X.25 |
| Hangungmal | kor-001 | X.25 |
| Nederlands | nld-000 | X.25 |
| polski | pol-000 | X.25 |
| português | por-000 | X.25 |
| русский | rus-000 | X.25 |
| svenska | swe-000 | X.25 |
| ภาษาไทย | tha-000 | X.25 |
| Türkçe | tur-000 | X.25 |
| English | eng-000 | X25 Address |
| Türkçe | tur-000 | X25 Adresi |
| Türkçe | tur-000 | X.25 Arama Grubu |
| Türkçe | tur-000 | X.25 bağlandı |
| English | eng-000 | X.25 connected |
| English | eng-000 | X.25 diagnostic indication |
| English | eng-000 | X25 Facilities |
| English | eng-000 | X.25 Hunt Group |
| Türkçe | tur-000 | X25 Kullanıcı Verisi |
| English | eng-000 | X.25 network-recommendation |
| Türkçe | tur-000 | X25 Olanakları |
| Türkçe | tur-000 | X25 Pad Türü |
| English | eng-000 | X25 Pad Type |
| hrvatski | hrv-000 | X. 25- priopćajni protokol |
| English | eng-000 | X.25 Routing |
| English | eng-000 | X25 Routing |
| English | eng-000 | X.25 standards |
| Türkçe | tur-000 | X.25 standartları |
| Türkçe | tur-000 | X.25 tanı belirlemesi |
| English | eng-000 | X25 User Data |
| Türkçe | tur-000 | X25 Yapılandır |
| Türkçe | tur-000 | X25 Yönlendirme |
| English | eng-000 | X-26 Frigate |
| English | eng-000 | X-28 Sea Skimmer |
| עברית | heb-000 | X-29 |
| 日本語 | jpn-000 | X-29 |
| magyar | hun-000 | X–29 |
| English | eng-000 | X² chart |
| English | eng-000 | X² criterion |
| English | eng-000 | X² distribution |
| Hànyǔ | cmn-003 | X2 fēn bù |
| Hànyǔ | cmn-003 | X2fēn bù |
| English | eng-000 | X² method |
| English | eng-000 | X² minimum method |
| Proto-Malayo-Polynesian | poz-000 | *X₂ + qatay |
| magyar | hun-000 | X–2 Starbuster |
| English | eng-000 | X²-T² |
| English | eng-000 | X² test |
| English | eng-000 | X2: The Threat |
| polski | pol-000 | X2: The Threat |
| русский | rus-000 | X2: The Threat |
| English | eng-000 | X2: Wolverine’s Revenge |
| suomi | fin-000 | X2: Wolverine’s Revenge |
| Nederlands | nld-000 | X2: Wolverine’s Revenge |
| español | spa-000 | X2: Wolverine’s Revenge |
| srpski | srp-001 | X2: X-Men United |
| עברית | heb-000 | X-2 סטארבסטר |
| 普通话 | cmn-000 | X2分布 |
| 普通话 | cmn-000 | Ｘ²检验 |
| 普通话 | cmn-000 | X²检验的修正 |
| English | eng-000 | X²检验的修正 |
| 國語 | cmn-001 | X-2試驗機 |
| 日本語 | jpn-000 | X-3 |
| English | eng-000 | X3 |
| Baip‧ngvp‧zix | bca-000 | x3 |
| Dashi Bai | bca-001 | x3 |
| Jinxing Bai | bca-006 | x3 |
| Boikin—Pogo-Rawo | bzf-002 | x3 |
| Ojitlán | chj-000 | x3 |
| Xiang | hsn-001 | x3 |
| Lisu | lis-000 | x3 |
| Naqxi | nxq-000 | x3 |
| Suyá | suy-000 | x3 |
| šʹəbzá | uby-001 | x3 |
| Lalo | ywt-001 | x3 |
| Nanjiang | ywt-002 | x3 |
| Fengshan | zgn-000 | x3 |
| 日本語 | jpn-000 | X-30 |
| 日本語 | jpn-000 | X-31 |
| magyar | hun-000 | X–31 |
| dansk | dan-000 | X-32 |
| עברית | heb-000 | X-32 |
| 日本語 | jpn-000 | X-32 |
| magyar | hun-000 | X–32 |
| filename extensions | art-335 | x32 |
| TechTarget file types | art-336 | X32-Macromedia-Extra-program-extension-32-bit |
| Deutsch | deu-000 | X-33 |
| français | fra-000 | X-33 |
| 日本語 | jpn-000 | X-33 |
| português | por-000 | X-33 |
| русский | rus-000 | X-33 |
| English | eng-000 | X-33, X-34 |
| 日本語 | jpn-000 | X-34 |
| русский | rus-000 | X-34 |
| 日本語 | jpn-000 | X-36 |
| Nanjiang | ywt-002 | x37 |
| námetejemi̵naa | bmr-000 | x37ai |
| Deutsch | deu-000 | X-38 |
| polski | pol-000 | X-38 |
| Algerian Spoken Arabic | arq-000 | X38ma |
| 國語 | cmn-001 | X-38試驗機 |
| Saho | ssy-000 | X3b |
| Kichee de Chichicastenango | quc-014 | X3b" |
| Qafár af | aar-000 | X3b3l |
| námetejemi̵naa | bmr-000 | x3bege7i |
| Glavda | glw-000 | x3bu |
| Samish | str-003 | X3C |
| Vaghua | tva-000 | x3c |
| Nooksack | nok-000 | x3c3m |
| Mafa—Magumaz | maf-000 | x3can |
| Tigré | tig-001 | X3c"at |
| Nymylan | kpy-000 | x3CCi |
| Samish | str-003 | X3CN |
| Diegueno | dih-001 | x3Cur |
| 普通话 | cmn-000 | X3D |
| 國語 | cmn-001 | X3D |
| Deutsch | deu-000 | X3D |
| English | eng-000 | X3D |
| italiano | ita-000 | X3D |
| polski | pol-000 | X3D |
| português | por-000 | X3D |
| español | spa-000 | X3D |
| svenska | swe-000 | X3D |
| Türkçe | tur-000 | X3D |
| Giʼiz | gez-001 | X3d |
| filename extensions | art-335 | x3d |
| budad mez | bdk-000 | x3d |
| Rendille | rel-000 | x3d3X |
| Cineni | cie-000 | x3da |
| Boga | bvw-000 | x3da7a |
| Warji | wji-000 | x3dai |
| English | eng-000 | x3d and xdart Formats |
| filename extensions | art-335 | x3db |
| English | eng-000 | X3D Binary Format File |
| TechTarget file types | art-336 | X3DB-X3D-Binary-Format-File-Web3D-Consortium |
| filename extensions | art-335 | x3dbz |
| TechTarget file types | art-336 | X3DBZ-X3D-GZipped-Binary-Format-File-Web3D-Consortium |
| English | eng-000 | X3D Classic VRML File |
| Jimi | jim-000 | x3ddan |
| English | eng-000 | X3D File |
| English | eng-000 | X3D file Header |
| English | eng-000 | X3D GZipped Binary Format File |
| English | eng-000 | X3D GZipped Classic VRML File |
| Sōreth | cld-001 | x3dia |
| filename extensions | art-335 | x3dv |
| TechTarget file types | art-336 | X3DV-X3D-Classic-VRML-File-Web3D-Consortium |
| filename extensions | art-335 | x3dvz |
| TechTarget file types | art-336 | X3DVZ-X3D-GZipped-Classic-VRML-File-Web3D-Consortium |
| TechTarget file types | art-336 | X3D-x3d-and-xdart-Formats |
| TechTarget file types | art-336 | X3D-X3D-File |
| TechTarget file types | art-336 | X3D-X3D-file-Header |
| المغربية | ary-000 | X3dX~3m |
| TechTarget file types | art-336 | X3D-Xara-3D-project-file |
| filename extensions | art-335 | x3f |
| Bafmeng | bfm-000 | x3f |
| TechTarget file types | art-336 | X3F-Foveon-X3F-RAW-format-image |
| TechTarget file types | art-336 | X3F-Sigma-Camera-RAW-Picture-File-Sigma |
| Abam | gdr-002 | X3ga |
| Dorogori | gdr-003 | X3ga |
| Gamaewe | gdr-004 | X3ga |
| Kapal | gdr-007 | X3ga |
| Wonie | gdr-012 | X3ga |
| námetejemi̵naa | bmr-000 | x3gasu7i |
| evedȳ turēn | evn-004 | x3gd3g3 |
| evedȳ turēn | evn-004 | x3gdi |
| Kansa | ksk-000 | x3ha |
| Oksapmin | opm-000 | x3ima |
| Mbizinaku | bkm-001 | x3in |
| Algerian Spoken Arabic | arq-000 | X3jra |
| nɬeʔkepmxcín | thp-000 | X3k |
| Kui | kvd-000 | x3kakalal |
| námetejemi̵naa | bmr-000 | x3kku |
| námetejemi̵naa | bmr-000 | x3ku |
| evedȳ turēn | evn-004 | x3ku |
| 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 |