XTerm.NET

Tested Software version 3.0.2 on Linux. XTerm.NET is a headless emulator library; tested through the Example desktop application of its Avalonia host, Iciclecreek.Avalonia.Terminal. The homepage URL of this terminal is https://github.com/tomlm/XTerm.NET. Full results available at ucs-detect repository path data/xtermnet.yaml.

Score Breakdown

Detailed breakdown of how scores are calculated for XTerm.NET:

#	Score Type	Raw Score	Final Scaled Score
1	WIDE	100.00%	100.0%
2	NARROW	100.00%	100.0%
3	ZWJ	100.00%	100.0%
4	LANG	100.00%	100.0%
5	VS16	100.00%	100.0%
6	VS15	100.00%	(excluded)
7	SRI	100.00%	100.0%
8	SFZ	100.00%	100.0%
9	RI	100.00%	100.0%
10	FEAT	94.44%	94.4%
11	Graphics	100%	100.0%
12	Resources	44.1%	44.1%

Score Comparison Plot:

The following plot shows how this terminal’s scores compare to all other terminals tested.

Scaled scores comparison across all metrics (normalized 0-100%)

Final Scaled Score Calculation:

• Raw Final Score: 99.32% (weighted average: WIDE + NARROW + ZWJ + LANG + VS16 + 0.33 * SRI + 0.33 * SFZ + RI + CAP + 0.5 * GFX) the categorized ‘average’ absolute support level of this terminal.

  Note

  RSC (Resources) is a composite CPU, memory, and runtime score, displayed for comparison but excluded from the final score FEAT (Features) is the fraction of notable features supported. GFX (Graphics) scores 100% for modern protocols (iTerm2, Kitty), 50% for legacy only (Sixel, ReGIS), 0% for none.

• Final Scaled Score: 99.0% (normalized across all terminals tested). Final Scaled scores are normalized (0-100%) relative to all terminals tested

WIDE Score Details:

Wide character support calculation:

• Total successful contested codepoints: 553

• Total contested codepoints tested: 1529

• Formula: 553 / 1529

• Result: 100.00% † (Text Sizing protocol)

NARROW Score Details:

Narrow character support calculation:

• Total successful contested codepoints: 6589

• Total contested codepoints tested: 6589

• Formula: 6589 / 6589

• Result: 100.00%

ZWJ Score Details:

Emoji ZWJ (Zero-Width Joiner) support calculation:

• Total successful sequences: 1445

• Total sequences tested: 1445

• Formula: 1445 / 1445

• Result: 100.00%

VS16 Score Details:

Variation Selector-16 support calculation:

• Errors: 0 of 426 codepoints tested

• Success rate: 100.0%

• Formula: 100.0 / 100

• Result: 100.00%

Variation Selector-15 support:

Note

Interpretation of VS-15 is contested. Its width behavior is not consistently implemented across terminals; this measurement is informational and excluded from final scoring.

Variation Selector-15 support calculation:

• Errors: 0 of 158 codepoints tested

• Success rate: 100.0%

• Formula: 100.0 / 100

• Result: 100.00%

SRI Score Details:

Standalone Regional Indicator support calculation:

• Total successful codepoints: 26

• Total codepoints tested: 26

• Formula: 26 / 26

• Result: 100.00%

SFZ Score Details:

Standalone Fitzpatrick skin tone modifier support calculation:

• Total successful codepoints: 5

• Total codepoints tested: 5

• Formula: 5 / 5

• Result: 100.00%

RI Score Details:

Regional Indicator flag sequence support calculation:

• Total successful sequences: 262

• Total sequences tested: 262

• Formula: 262 / 262

• Result: 100.00%

Features Score Details:

Notable terminal features (17.0 / 18):

• Set bracketed paste mode (2004): yes

• Synchronized Output (2026): yes

• In-Band Window Resize Notifications (2048): yes

• Send FocusIn/FocusOut events (1004): yes

• Enable SGR Mouse Mode (1006): yes

• Grapheme Clustering (2027): yes

• Bracketed Paste MIME (5522): yes

• Kitty Keyboard (Full): yes

• XTGETTCAP (Full): yes

• Text Sizing (OSC 66): yes

• Tofu Detection: no

• Kitty Clipboard Protocol: yes

• OSC 52 Clipboard: yes

• Kitty Pointer Shapes (OSC 22): yes

• Kitty Notifications (OSC 99): yes

• Color Report (OSC 10/11): yes

• Terminal Identification (XTVERSION): yes

• Truecolor Detection: yes

• DECRQCRA: yes

Raw score: 94.44%

Graphics Score Details:

Graphics protocol support (100%):

• Sixel: yes

• ReGIS: no

• iTerm2: no

• Kitty: yes

Scoring: 100% for modern (iTerm2/Kitty), 50% for legacy only (Sixel/ReGIS), 0% for none

Resource Score Details:

• Duration: 2.0s

• Mean CPU: 164.2%

• Mean RSS: 202.3 MB

• Resources Score: 44/100

• Note: log-scale composite cost = log(CPU+1) + log(RSS+1) + log(time+1)

• Scaled result: 44.1%

LANG Score Details (Geometric Mean):

Geometric mean calculation:

• Formula: (p₁ × p₂ × … × pₙ)^(1/n) where n = 85 contested languages

• About geometric mean

• Result: 100.00% † (Text Sizing protocol)

Wide character support

Wide character support of XTerm.NET is 36.2% (976 errors of 1529 codepoints tested).

Sequence of a WIDE character, from midpoint of alignment failure records:

#	Codepoint	Python	Category	wcwidth	Name
1	U+00018FE8	‘\U00018fe8’	Cn	2	na

Total codepoints: 1

• Shell test using printf(1), '|' should align in output:

  $ printf "\xf0\x98\xbf\xa8|\\n12|\\n"
  𘿨|
  12|
  

Screenshot:

• python wcwidth.wcswidth() measures width 2, while XTerm.NET measures width 1.

Narrow character support

Narrow character support of XTerm.NET is 100.0% (0 errors of 6589 codepoints tested).

Emoji ZWJ support

Compatibility of XTerm.NET with the Unicode Emoji ZWJ sequence table is 100.0% (0 errors of 1445 sequences tested).

Variation Selector-16 support

Emoji VS-16 results for XTerm.NET is 0 errors out of 426 total codepoints tested, 100.0% success. All codepoint combinations with Variation Selector-16 tested were successful.

Variation Selector-15 support

Emoji VS-15 results for XTerm.NET is 0 errors out of 158 total codepoints tested, 100.0% success. All codepoint combinations with Variation Selector-15 tested were successful.

Standalone Regional Indicator support

Standalone Regional Indicator support of XTerm.NET is 100.0% (0 errors of 26 codepoints tested).

Standalone Fitzpatrick modifier support

Standalone Fitzpatrick skin tone modifier support of XTerm.NET is 100.0% (0 errors of 5 codepoints tested).

Regional Indicator flag sequence support

Regional Indicator flag sequence support of XTerm.NET is 100.0% (0 errors of 262 sequences tested).

Graphics Protocol Support

XTerm.NET supports the following graphics protocols: Sixel, Kitty graphics.

Detection Methods:

• Sixel and ReGIS: Sixel: Detected; ReGIS: Not detected via the Device Attributes (DA1) query CSI c (\x1b[c). Sixel indicator (4): present, ReGIS indicator (3): not present.

• Kitty graphics: Detected by sending a Kitty graphics query and checking for an OK response.

• iTerm2 inline images: Not detected by drawing a 1x1 transparent image, OSC 1337 ; File=inline=1, and checking that the cursor advanced a single column.

• iTerm2 capabilities: Detected via the OSC 1337 ; Capabilities query, which does not describe image support, and does not contribute to this score.

Device Attributes

• Raw response: '\x1b[?65;4;1;2;6;9;15;16;17;18;21;22;28;29c'

• Service class: 65 (VT525)

Detected Extensions:

Code	Description
1	132-column mode
2	Printer port
4	Sixel graphics
6	Selective erase
9	National replacement charsets
15	Technical character set
16	unknown
17	Terminal state reports (16-bit)
18	User windows
21	Horizontal scrolling
22	ANSI color
28	Rectangular area operations
29	Text locator (mouse)

Language Support

The following 84 languages were tested with 100% success:

Aja, Amarakaeri, Arabic, Standard, Assyrian Neo-Aramaic, Baatonum, Bamun, Belanda Viri, Bengali, Bhojpuri, Bora, Burmese, Catalan (2), Chakma, Chickasaw, Chinantec, Chiltepec, Dagaare, Southern, Dari, Dendi, Dinka, Northeastern, Dzongkha, Evenki, Farsi, Western, Fon, French (Welche), Fur, Ga, Gen, Gilyak, Gujarati, Gumuz, Hindi, Javanese (Javanese), Kabyle, Kannada, Khmer, Central, Lamnso’, Lao, Lingala (tones), Magahi, Maithili, Malayalam, Maldivian, Maori (2), Marathi, Mazahua Central, Mon, Mòoré, Nanai, Navajo, Nepali, Orok, Otomi, Mezquital, Panjabi, Eastern, Panjabi, Western, Pashto, Northern, Picard, Pular (Adlam), Sanskrit, Sanskrit (Grantha), Secoya, Seraiki, Shan, Shipibo-Conibo, Sinhala, Siona, South Azerbaijani, Tagalog (Tagalog), Tai Dam, Tamang, Eastern, Tamazight, Central Atlas, Tamil, Telugu, Tem, Thai, Thai (2), Tibetan, Central, Ticuna, Uduk, Urdu, Urdu (2), Vietnamese, Yaneshaʼ, Yiddish, Eastern, Yoruba.

The following 1 languages are not fully supported:

lang	n_errors	n_total	pct_success
Khün	17	421	96.0%

Khün

Sequence of language Khün from midpoint of alignment failure records:

#	Codepoint	Python	Category	wcwidth	Name
1	U+1A63	‘\u1a63’	Mc	0	TAI THAM VOWEL SIGN AA
2	U+1A60	‘\u1a60’	Mn	0	TAI THAM SIGN SAKOT
3	U+1A20	‘\u1a20’	Lo	1	TAI THAM LETTER HIGH KA

Total codepoints: 3

• Shell test using printf(1), '|' should align in output:

  $ printf "\xe1\xa9\xa3\xe1\xa9\xa0\xe1\xa8\xa0|\\n12|\\n"
  ᩣ᩠ᨠ|
  12|
  

Screenshot:

• python wcwidth.wcswidth() measures width 2, while XTerm.NET measures width 1.

DEC Private Modes Support

DEC private modes results for XTerm.NET: 6 changeable modes of 7 supported out of 8 total modes tested (87.5% support, 75.0% changeable).

Complete list of DEC private modes tested:

Mode	Name	Description	Supported	Changeable	Enabled
1004	FOCUS_IN_OUT_EVENTS	Send FocusIn/FocusOut events	Yes	Yes	No
1006	MOUSE_EXTENDED_SGR	Enable SGR Mouse Mode	Yes	Yes	No
2004	BRACKETED_PASTE	Set bracketed paste mode	Yes	Yes	No
2026	SYNCHRONIZED_OUTPUT	Synchronized Output	Yes	Yes	No
2027	GRAPHEME_CLUSTERING	Grapheme Clustering	Yes	No	Yes
2031	COLOR_PALETTE_UPDATES	Color palette updates	No	No	No
2048	IN_BAND_WINDOW_RESIZE	In-Band Window Resize Notifications	Yes	Yes	No
5522	BRACKETED_PASTE_MIME	Bracketed Paste MIME	Yes	Yes	No

Summary: 6 changeable, 2 not changeable.

DECRQCRA

Request Checksum of Rectangular Area (DECRQCRA) allows an application running in the terminal to read a checksum of any rectangular region of the screen.

XTerm.NET answers DECRQCRA queries.

Error

Any program that can write to the terminal, including a compromised remote host, can read the contents of the primary and alternate terminal screen contents through ‘screen scraping’. Though useful for compliance testing with tools like esctest, release builds of terminals should disable it by default: see wezterm PR 7701 and ANSI terminal security in 2023: cursor checksum for details.

Kitty Keyboard Protocol

XTerm.NET supports the Kitty keyboard protocol.

#	Flag	Key	Supported
1	Disambiguate escape codes	disambiguate	Yes
2	Report event types	report_events	Yes
3	Report alternate keys	report_alternates	Yes
4	Report all keys as escape codes	report_all_keys	Yes
5	Report associated text	report_text	Yes

Detection is performed by enabling all progressive enhancement modes by set (CSI = 31 ; 1 u) and re-querying with CSI ? u to confirm which modes the terminal honors, before restoring its original flags.

XTGETTCAP (Terminfo Capabilities)

XTerm.NET supports the XTGETTCAP sequence and reports 88 terminfo capabilities (Full).

#	Capability	Description	Value
1	Ms	Clipboard set	\E]52;%p1%s;%p2%s\a
2	RGB	Bits per color channel (8 = 24-bit truecolor)	8/8/8
3	Setulc	Set underline color	\E[58:2::%p1%{65536}%/%d:%p1%{256}%/%{255}%&%d:%p1%{255}%...
4	Smulx	Styled underline	\E[4:%p1%dm
5	Su	Colored underlines	(empty)
6	TN	Terminal name	xterm
7	Tc	Truecolor (24-bit RGB)	(empty)
8	bel	Bell	\a
9	blink	Enter blink mode	\E[5m
10	bold	Enter bold mode	\E[1m
11	civis	Hide cursor	\E[?25l
12	clear	Clear screen	\E[H\E[2J
13	cnorm	Normal cursor	\E[?25h
14	colors	Max colors on screen	256
15	cols	Columns	76
16	cr	Carriage return	\r
17	csr	Change scroll region	\E[%i%p1%d;%p2%dr
18	cub	Cursor left n	\E[%p1%dD
19	cub1	Cursor left	\b
20	cud	Cursor down n	\E[%p1%dB
21	cud1	Cursor down	\n
22	cuf	Cursor right n	\E[%p1%dC
23	cuf1	Cursor right	\E[C
24	cup	Cursor address	\E[%i%p1%d;%p2%dH
25	cuu	Cursor up n	\E[%p1%dA
26	cuu1	Cursor up	\E[A
27	dch	Delete n characters	\E[%p1%dP
28	dch1	Delete character	\E[P
29	dim	Enter dim mode	\E[2m
30	dl	Delete n lines	\E[%p1%dM
31	dl1	Delete line	\E[M
32	ech	Erase characters	\E[%p1%dX
33	ed	Clear to end of screen	\E[J
34	el	Clear to end of line	\E[K
35	el1	Clear to start of line	\E[1K
36	home	Cursor home	\E[H
37	hpa	Horizontal position	\E[%i%p1%dG
38	ht	Horizontal tab	\t
39	ich	Insert n characters	\E[%p1%d@
40	ich1	Insert character	\E[@
41	il	Insert n lines	\E[%p1%dL
42	il1	Insert line	\E[L
43	ind	Scroll forward	\n
44	invis	Invisible cursor	\E[8m
45	kbs	Backspace key	
46	kcbt	Back-tab key	\E[Z
47	kcub1	Left arrow key	\EOD
48	kcud1	Down arrow key	\EOB
49	kcuf1	Right arrow key	\EOC
50	kcuu1	Up arrow key	\EOA
51	kdch1	Delete character key	\E[3~
52	kend	End key	\E[F
53	kf1	Function key F1	\EOP
54	kf10	Function key F10	\E[21~
55	kf11	Function key F11	\E[23~
56	kf12	Function key F12	\E[24~
57	kf2	Function key F2	\EOQ
58	kf3	Function key F3	\EOR
59	kf4	Function key F4	\EOS
60	kf5	Function key F5	\E[15~
61	kf6	Function key F6	\E[17~
62	kf7	Function key F7	\E[18~
63	kf8	Function key F8	\E[19~
64	kf9	Function key F9	\E[20~
65	khome	Home key	\E[H
66	kich1	Insert character key	\E[2~
67	knp	Next page key	\E[6~
68	kpp	Previous page key	\E[5~
69	lines	Lines	21
70	rc	Restore cursor	\E8
71	rep	Repeat character	%p1%c\E[%p2%{1}%-%db
72	rev	Enter reverse mode	\E[7m
73	ri	Reverse index	\EM
74	ritm	Exit italics mode	\E[23m
75	rmcup	Exit alt screen	\E[?1049l
76	rmkx	Keypad local mode	\E[?1l\E>
77	rmso	Exit standout mode	\E[27m
78	rmul	Exit underline mode	\E[24m
79	sc	Save cursor	\E7
80	setrgbb	Set RGB background	\E[48:2:%p1%d:%p2%d:%p3%dm
81	setrgbf	Set RGB foreground	\E[38:2:%p1%d:%p2%d:%p3%dm
82	sgr0	Reset attributes	\E(B\E[m
83	sitm	Enter italics mode	\E[3m
84	smcup	Enter alt screen	\E[?1049h
85	smkx	Keypad transmit mode	\E[?1h\E=
86	smso	Enter standout mode	\E[7m
87	smul	Enter underline mode	\E[4m
88	vpa	Vertical position	\E[%i%p1%dd

The XTGETTCAP sequence (DCS + q Pt ST) allows applications to query terminfo capabilities directly from the terminal emulator, rather than relying on the system terminfo database.

Text Sizing Protocol (OSC 66)

XTerm.NET supports the Text Sizing protocol: explicit width (w), scale (s).

The Text Sizing protocol (OSC 66) allows terminal programs to display text at different sizes and to explicitly specify the cell width of characters. Detection is performed by measuring cursor movement after sending ESC ] 66 ; w=2 ; <space> BEL and ESC ] 66 ; s=2 ; <space> BEL.

Because this terminal supports the Text Sizing protocol, any application can programmatically set the displayed cell width of any character. This means that width errors for complex languages, emoji, variation selectors (VS15, VS16), standalone regional indicators and Fitzpatrick modifiers, and other problematic codepoints can be fully remediated at the application level. For this reason, XTerm.NET is credited 100% on the WIDE and LANG width tests, where it measured below 100% or was not measured at all. Every other width score was measured directly.

Tofu Detection

A tofu is the □ U+25A1 WHITE SQUARE placeholder box drawn in place of a codepoint the terminal’s font has no glyph for. Two protocols allow a program to ask which codepoints may ‘tofu’: mintty’s Font Glyph Coverage Enquiry and the Glyph Protocol implemented first by Rio.

XTerm.NET does not answer a font glyph coverage enquiry by either protocol, ‘tofus’ cannot be determined by automatic code.

Truecolor Support

XTerm.NET supports 24-bit truecolor, detectable via:

• XTGETTCAP (RGB capability): yes (RGB)

• DECRQSS (truecolor probe): yes (probe)

• COLORTERM: yes (truecolor)

OSC 52 Clipboard Support

XTerm.NET supports OSC 52 clipboard operations (detected via XTGETTCAP Ms).

• DA1 extension 52: no

• XTGETTCAP Ms: yes

Terminal Identification

XTerm.NET is identified as XTerm.NET version 3.0.2 (detected via XTVERSION).

• XTVERSION (raw): XTerm.NET(3.0.2)

• XTVERSION: yes

• XTGETTCAP TN: yes (xterm)

• ENQ: no

• TERM_PROGRAM: no

• TERM: no (xterm-256color)

Reproduction

To reproduce these results for XTerm.NET, install and run ucs-detect with the following commands:

uvx ucs-detect --rerun data/xtermnet.yaml

Test Performance

The test suite completed in 2.01 seconds (2s).

• Mean CPU: 164.2%

• Mean RSS: 202.3 MB

• Total time: 2.0s

CPU usage during test execution for XTerm.NET.

RSS memory usage during test execution for XTerm.NET.

Test duration for XTerm.NET compared to all other terminals.

CPU % vs duration trade-off for XTerm.NET.