From 84c9a581a27074b5481e2c169f355830fc1f303f Mon Sep 17 00:00:00 2001
From: Mc-Zen <52877387+Mc-Zen@users.noreply.github.com>
Date: Sat, 28 Mar 2026 15:02:07 +0100
Subject: [PATCH 1/9] [test] fraction

---
 tests/zi/fraction/.gitignore |  5 +++++
 tests/zi/fraction/ref.typ    | 23 +++++++++++++++++++++++
 tests/zi/fraction/test.typ   | 26 ++++++++++++++++++++++++++
 3 files changed, 54 insertions(+)
 create mode 100644 tests/zi/fraction/.gitignore
 create mode 100644 tests/zi/fraction/ref.typ
 create mode 100644 tests/zi/fraction/test.typ

diff --git a/tests/zi/fraction/.gitignore b/tests/zi/fraction/.gitignore
new file mode 100644
index 0000000..2e4c5d8
--- /dev/null
+++ b/tests/zi/fraction/.gitignore
@@ -0,0 +1,5 @@
+# generated by tytanic, do not edit
+
+/diff/
+/out/
+/ref/
diff --git a/tests/zi/fraction/ref.typ b/tests/zi/fraction/ref.typ
new file mode 100644
index 0000000..2d6adfd
--- /dev/null
+++ b/tests/zi/fraction/ref.typ
@@ -0,0 +1,23 @@
+#set page(width: auto, height: auto, margin: .5em)
+
+#let th = sym.space.thin
+
+$"m"th "s"^(-1)$ \
+$"m"\/"s"$ \
+$"m"/"s"$ \
+
+$"m"th "s"^(-1) th "N"^(-1)$ \
+$"m"\/("s"th"N")$ \
+$"m"/("s"th"N")$ \
+
+#pagebreak()
+
+#set super(typographic: false)
+
+m#th;s#super[−1] \
+m/s \
+m/s \
+
+m#th;s#super[−1]#th;N#super[−1] \
+m/(s#th;N) \
+m/(s#th;N) \
diff --git a/tests/zi/fraction/test.typ b/tests/zi/fraction/test.typ
new file mode 100644
index 0000000..3cf7317
--- /dev/null
+++ b/tests/zi/fraction/test.typ
@@ -0,0 +1,26 @@
+#set page(width: auto, height: auto, margin: .5em)
+#import "/src/zero.typ": set-unit, set-num, zi
+
+
+#let m-s-N = zi.declare("m/s/N")
+
+#zi.m-s() \
+#zi.m-s(fraction: "inline") \
+#zi.m-s(fraction: "fraction") \
+
+#m-s-N() \
+#m-s-N(fraction: "inline") \
+#m-s-N(fraction: "fraction") \
+
+
+#pagebreak()
+#set-num(math: false)
+
+#zi.m-s() \
+#zi.m-s(fraction: "inline") \
+#zi.m-s(fraction: "fraction") \
+
+
+#m-s-N() \
+#m-s-N(fraction: "inline") \
+#m-s-N(fraction: "fraction") \
\ No newline at end of file

From 065963a589a3c0c7adaf59db4601f43ad6a11739 Mon Sep 17 00:00:00 2001
From: Mc-Zen <52877387+Mc-Zen@users.noreply.github.com>
Date: Sat, 28 Mar 2026 15:03:20 +0100
Subject: [PATCH 2/9] [add] utility for processing dict breakable arguments

---
 src/utility.typ | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/src/utility.typ b/src/utility.typ
index 9dfb6e8..b1bb636 100644
--- a/src/utility.typ
+++ b/src/utility.typ
@@ -43,3 +43,27 @@
 #assert.eq(shift-decimal-left("123", "456", digits: -5), ("12345600", ""))
 #assert.eq(shift-decimal-left("0", "0012", digits: -4), ("12", ""))
 #assert.eq(shift-decimal-left("0", "0012", digits: -2), ("0", "12"))
+
+
+#let process-breakable(breakable) = {
+  let default = (
+    uncertainty: false,
+    power: false,
+    unit: false,
+  )
+
+  if breakable == false {
+    return default
+  }
+  if breakable == true {
+    return (
+      uncertainty: true,
+      power: true,
+      unit: true,
+    )
+  }
+  if type(breakable) == dictionary {
+    return default + breakable
+  }
+  assert(false)
+}

From 2bf409d26300029f87f69061784fefaca285afd7 Mon Sep 17 00:00:00 2001
From: Mc-Zen <52877387+Mc-Zen@users.noreply.github.com>
Date: Sat, 28 Mar 2026 15:12:42 +0100
Subject: [PATCH 3/9] [refactor] fractions

---
 src/units.typ               |  54 +++++++++++++++---------------------
 tests/zi/advanced/ref.typ   |  16 +++++++++++
 tests/zi/advanced/ref/1.png | Bin 2458 -> 0 bytes
 tests/zi/advanced/ref/2.png | Bin 594 -> 0 bytes
 4 files changed, 38 insertions(+), 32 deletions(-)
 create mode 100644 tests/zi/advanced/ref.typ
 delete mode 100644 tests/zi/advanced/ref/1.png
 delete mode 100644 tests/zi/advanced/ref/2.png

diff --git a/src/units.typ b/src/units.typ
index c72c956..12277dd 100644
--- a/src/units.typ
+++ b/src/units.typ
@@ -184,6 +184,13 @@
   /// Unprocessed arguments.
   ..args,
 ) = {
+  assert(
+    fraction in ("power", "fraction", "inline"),
+    message: "Invalid fraction: "
+      + fraction
+      + ". Expected \"power\", \"fraction\", or \"inline\"",
+  )
+
   let fold-units = fold-units.with(
     unit-separator: unit-separator,
     math: math,
@@ -200,7 +207,7 @@
   let denominator-content = fold-units(..denominator, denom-exp-multiplier)
 
   if fraction == "power" {
-    // Numerator may be empty!
+    // Numerator could be empty!
     let result = denominator-content
     if numerator.len() != 0 {
       result = numerator-content + unit-separator + result
@@ -211,34 +218,21 @@
   // For the two fractional modes, the numerator shall not be empty.
   if numerator.len() == 0 { numerator-content = $1$ }
 
-  if fraction == "fraction" {
-    if not math {
-      assert(
-        false,
-        "`math: false` cannot be used together with `fraction: \"fraction\"`",
-      )
+  if math {
+    if denominator.len() > 1 and fraction == "inline" {
+      denominator-content = $(#denominator-content)$
     }
-    return $#numerator-content/#denominator-content$
-  } else if fraction == "inline" {
+    set std.math.frac(style: "horizontal") if fraction == "inline"
+    $#numerator-content/#denominator-content$
+  } else {
     if denominator.len() > 1 {
-      denominator-content = "(" + denominator-content + ")"
-    }
-
-    if math {
-      $#numerator-content#h(0pt)\/#h(0pt)#denominator-content$
-    } else {
-      numerator-content + "/" + denominator-content
+      denominator-content = [(#denominator-content)]
     }
-  } else {
-    assert(
-      false,
-      message: "Invalid fraction: "
-        + fraction
-        + ". Expected \"power\", \"fraction\", or \"symbol\"",
-    )
+    numerator-content + "/" + denominator-content
   }
 }
 
+
 #let unit(
   unit,
   ..args,
@@ -255,13 +249,6 @@
     ..num-state.unit,
     math: num-state.math,
   )
-  if not num-state.unit.breakable {
-    if num-state.math {
-      result = $result$
-    } else {
-      result = box(result)
-    }
-  }
   result
 }
 
@@ -319,10 +306,13 @@
       unit.numerator.first().first() = prefix + unit.numerator.first().first()
     }
   }
+  let breakable = utility.process-breakable(num-state.unit.breakable)
 
   let result = {
     num(value, state: num-state, force-parentheses-around-uncertainty: true)
+    sym.wj
     separator
+    if not breakable.unit { sym.wj }
     show-unit(
       unit.numerator,
       unit.denominator,
@@ -332,9 +322,9 @@
     )
   }
 
-  if not num-state.unit.breakable {
+  if not breakable.power {
     if num-state.math {
-      result = $result$
+      result = box($result$)
     } else {
       result = box(result)
     }
diff --git a/tests/zi/advanced/ref.typ b/tests/zi/advanced/ref.typ
new file mode 100644
index 0000000..0c94381
--- /dev/null
+++ b/tests/zi/advanced/ref.typ
@@ -0,0 +1,16 @@
+#set page(width: auto, height: auto, margin: .5em)
+
+#let th = sym.space.thin
+
+$Pi^2$ \
+$"M"_dot.o\/("s"^2 th"β"^2)$ \
+$1\/("M"_dot.o th √"s"th"β"^"a")$ \
+$#sym.prime.double^2$
+
+
+#pagebreak()
+
+$"L"$ \
+$"mL"$ \
+$"l"$ \
+$"ml"$ \
diff --git a/tests/zi/advanced/ref/1.png b/tests/zi/advanced/ref/1.png
deleted file mode 100644
index 598c07d521b1c5cd39f17d900222c5f2e7f894c6..0000000000000000000000000000000000000000
GIT binary patch
literal 0
HcmV?d00001

literal 2458
zcmV;L31#+)P)<h;3K|Lk000e1NJLTq005W(004am00000dm#19000SLNkl<Zc-rmQ
zX;>BY9>DQtT);rRX_n@-GILEUpR_dfnxW-_8>SL?V@U)>B}>f~3`xrZx6~&ENv~Y5
zC?OXkrS3Hl5Hc#XFfffpMHX3P-wx+{otbl<<2lcP4(FlU>FIo4%=64M^Wyu=|Cwk0
zzqtbob%!;~8fFdqV}&(cF1N_AeY00TG3m19g{3-!%3+|&;=+Q(0tgkp|GmS`JbX`&
z9uE(a+}ESW{fj8r2kaCs{@!75Q4mUyED_vLG(Yah?;qBn3wsB}8)M2XGHm05IxI0P
z@NGDF&ho<EdH%qGu&2u{F6^)<xetpAYpRvhTU?lyHOw0JCkVSD2p5pd5qvBtEM<6K
zJG(x^6PP>1&dz?AhvjXp)ymO2j9A00Vb(Bfm^JK=8Ft;*>Dl*cFeY)~^qDdLkFXjv
zRG?Kk<uU~$CN%+u;@xUE*=0MR`fbCS`sO1$z8$op@6U!qLLxd>tB|?Q2Ilq#5(CT$
z%bP!c{)_2oTz9#3nu0O0k0bkXF*-jzmk(bFQD~))_n1393n0WBSZ1RFc5gN#tUf)`
zMsPx7eK%pt_Z1l99E_xDY$FEN-c^c5>DW^Eymvkd)nF$i3)9V7$|oP~T!gIo#bH7r
zMpbpqN3w1g2F`VhMr-{^fJgjLY#dO4<hy6g3VUk15QOZ+fnh=sMje=p<a*y)^!+^i
z6lhIU1I&6B*(c+QP&mYz6;^6H6q$SNFtLTO$p?^ZU4*`if6L<Mb12lakc{v`66R7*
zlnTl2`DTT&P)r6WT0u);`CTiKjNXqdeP8hDj4O~eE4R8LAQ?rm2UVA<PugVwguYf;
zRqBW=>&_~(!oCze0D{t53=4Kfazo5Q^3IwcG6OqClGjJLMJz*+x16W@bhZfu2=5?W
zazN4ZxLIN92konX1+*A8G8V}<VkJOv4>d3^lI(EFVYFesl&4)v?-vKehf7jW4Buf^
z7#qY;NZQ$ASjIg~NRHl#Btbj~97)1J?ouRM`qp8<VU>AdS2~UX?=ooNtz5SpS=il3
zYKMsTx<uDwDAz|bLhr}G%*Ez~F;&c{SWJsy52Padq$jchub!g#SRn>-ypgCn_+h}&
z%gnGyVbz{fdSMxfwP+;_L=oFb4RAddep=so35H<{k<@i^!@&5r%nWPn)oUKQFx94M
zZv-uH$w%Q8fZ|8-20)Z2fd6O=!}=ph6}DqwU`X4;in=ucuL_$09uo2Z<{bgJ=#Yz~
z{;o?XYHZWwu)mZ5TUKBo+b#lNVgEApHQ6P$HLP&OU~$x%YA)F3Q?uSz6lVHgAapmf
zY$qh2jzMd7kQ~<CA)zpC!X*sDmM+<to!~m+2Mi?lX>M!S&B&M&F_HC<2MtlNCr*AI
zeU({i6kde@b9bQ?F%97InWC+)A1uMpFU!;?Uw<=Fg`q&dcG)O4%mX%01P(+2W%f7F
zs_TD+mi@96qnd|YXqPb69N^%~z@AuOuOm9)t7zF}AB;M>jCKiQP9us%Wx#~PpffqI
zl`wCNseh)Vox-96kfpl;Io)eP=laZYT2dX25o)(&+9?d551N5^hZ5lQyXeW=N82QP
zMZ1M@Xol-D$JI5KIPg|pvHl{khFQbf?oxtAd3%Osu0iq7T+CC@ZNfxFIxX6Dv#nu%
zny{nm;A})hL=swAx6Wetb+341AkS_3!v7+x$VQeur|Q?ja%XHsN7eg0k{_Lb=ygNI
zPI+iNCU#pDWXc1}Mqkm`^W;CZ5#Xb}`zK}~`R2t|!x|SnHb7X1&dEoSO*x0;<55BY
zim#^#PMBcTOBirF3!LwG4%A)$LD)!SPKm9BsZ+0}>V>&}faJ5O$o2<yeL#)OH(YSx
z*A?1lqOWEuK(p;O;Oo+FgYA)h{RFKqrCwNdx2s5|9?^vD@f5yLu6V|o6!z+T3?#n`
zP~Bk<5Hjww&uvjWlG28-@JUFDZEk48&Ik*Td=h6;Sdo1?l4}K2qlnrMaI|YK#CN_%
zvTfrRNLH?BL)i0SNJ2)S4P%&X34pUYPBbBG^$dXBE}PfRytf8fSaj)(DGPcY29ES<
zV1w<ogGi3uXL?wneFc(Lvvgs>;x^!?089zHVV?pdO#&|4+(fo7TD@z{uDPBnPz87e
zByW4I0!g}1ZgSYR`N*8SbYaCdBY-t|CWZMw3-IQX&A|9-P1rGjron;eyDpqFIc!u6
zvT<v5VayZH(zuA$!XoRC)%QLH5FreHD~WOxp;1Ua=w6AQTHy;*!!qw~ME3OUVJE~T
zL>_G=tZJdS6IsYuWb3;KLceHj*r!O23yJ8d6XHw_duu6*=U1Q$Ywp**W>I4+VeZE}
z4QK{v9vF+Hj^b#)-ks7kVgEuBZ}@wvOgLj|Sby!EOBSFD!(R+ojV?_6v6G{tZw}}<
zi;)0FMj~7B4N%-~1G13Uk?a(b(UU1$Yc(uI8%EMYXuLlG#numj><%3-=)%gT?{9*O
zbB>^sCXN9Z8Hvn$8Guu$CTv6lz_bB%==rLPx|OiZwB^F6Gv{joeEiW!w`&B*J~n7z
zYz|Bw3x(hNii1)!!Sh>WvvbjTMofYeL)Drvn;6I$UVv<`uSW?rYkQ`nZ__MV3G;UM
zT>P?!>m{JEXBJvRPXp|B_3&`r0pBIV;g@dR=)Q~`FBF+8(TNr3!1#kG-iuj3&%^r{
zG-1&R&Q9ZADZzllVH5Xb(W61@{a0u~_)%cP4}c@+4C`?5^g}9)*?SCQiu=@<81}*r
z(5e|yhH;yd;ig@%VOW^x^V}Yc+7pE_Z*Rl2u$%Tp=!6GiT>KWG2B?1lbQ=2D{I#Kl
zuun0fa%_`{VWHEwom)Ic)lF$cwl|F1y(ezNxTrY5kjnWiCWg(9;C3qaD;RZbsa%#a
z6FuebwX}i%X)tvu(Wg>l+`p%Mc>0jLPX%DU#@}MDtWOMzxMrQitzl+_-Mmm`iD9ah
zi(VV>Qmy5LMHE5mS=hK2ih8?QOxP*WpN3wK!t`N)%Uu=|Hvi6S4hbJa`hS2q{VXM{
zuyY_x7_CN@(`ARHgl!tsKt{(jWcB0xu#hnIgK@BYDYCk0A7LqBu`fW)z%nGYPA9<6
zLc$`iLS~%O<*+g|WY-i62s7X*Nd9hlVa+Ou+WHZ<hFQa`Vb(Bfm^I8AW(~83S;I{8
YKlnz#Z0oKt-2eap07*qoM6N<$f~>)yt^fc4

diff --git a/tests/zi/advanced/ref/2.png b/tests/zi/advanced/ref/2.png
deleted file mode 100644
index 5ef027d03237679fd60ae676468657cbf08bb3d6..0000000000000000000000000000000000000000
GIT binary patch
literal 0
HcmV?d00001

literal 594
zcmV-Y0<HatP)<h;3K|Lk000e1NJLTq001@s004am00000%(2g|0006RNkl<Zc-mw5
zPZnSp)i$b)ByC5vr38gU)%{4e?LHIJZ89ABlZol$sJ20&t&}WnFT=>vwyuyIZU3x#
zNYVC)iRl@Tx*Ni@oOo@=w1k<MBz1HInV6Ukkzm^|1Q;z#MzxJ<1A?T)l+=`@=%*xV
zyL?ERG4#-dpCmidhjAV`e)FZ3wr>~qZutN2)TT$kqU+4Yd&FuxZO1Nn(`Q--$K3m#
z6DM-?5bekq?uhUI|9grAeFCz1zY(h~ooNk_%ww7jBpaA+5wGnLkSt-k03_R(E}>}K
z`xTG2_h4;zz}haLX!HI-mNwo0<Y?PtfLmK4(@SuWTmuKmd61AB;~WrmUDX?xwmUWA
zOkr~$)ygyZPJ2<O%H%!qe_Js(qj_C@p$8jd8ZK?m)@<Ike$VSQo3?G(@qRUs-12|*
zayYm+T9%Az8|K=c&uptCL)*PF5gxJ}8AG17#8GXd+GwNg%NawaZI4OTb}=#`DSF0e
zSu(0^R2v+8zJKN&8QRP^nRbxl$VKF7+d9~^-6>Cr{lB*~y8qYzgJsbj--y)qbh?t@
zyyn*rM532hJby0dL9`=NSPOt;G)p3o%w>8-thRKf13<EvX+4l^Wx7VZwm0B@z%58W
z08Ja=?!#c#7RYoHNG32H2a<*0L92yKO9*K@sLsbP9dSm3pI_4Nx~71Dq|1LJ5dl$?
g(XwPz8$GoF0Fdh{VH^x3DgXcg07*qoM6N<$f(g$Vj{pDw


From 8f33490150ac9e781455dc07f490b5c72c3298c5 Mon Sep 17 00:00:00 2001
From: Mc-Zen <52877387+Mc-Zen@users.noreply.github.com>
Date: Sat, 28 Mar 2026 15:14:57 +0100
Subject: [PATCH 4/9] [tests] move out lowercase liter test

---
 tests/zi/declare-advanced/.gitignore             |  1 +
 tests/zi/{advanced => declare-advanced}/ref.typ  |  8 --------
 tests/zi/{advanced => declare-advanced}/test.typ | 10 ----------
 tests/zi/lowercase-liter/.gitignore              |  1 +
 tests/zi/lowercase-liter/ref.typ                 |  6 ++++++
 tests/zi/lowercase-liter/test.typ                |  8 ++++++++
 6 files changed, 16 insertions(+), 18 deletions(-)
 create mode 100644 tests/zi/declare-advanced/.gitignore
 rename tests/zi/{advanced => declare-advanced}/ref.typ (78%)
 rename tests/zi/{advanced => declare-advanced}/test.typ (74%)
 create mode 100644 tests/zi/lowercase-liter/.gitignore
 create mode 100644 tests/zi/lowercase-liter/ref.typ
 create mode 100644 tests/zi/lowercase-liter/test.typ

diff --git a/tests/zi/declare-advanced/.gitignore b/tests/zi/declare-advanced/.gitignore
new file mode 100644
index 0000000..2e73a39
--- /dev/null
+++ b/tests/zi/declare-advanced/.gitignore
@@ -0,0 +1 @@
+ref/
\ No newline at end of file
diff --git a/tests/zi/advanced/ref.typ b/tests/zi/declare-advanced/ref.typ
similarity index 78%
rename from tests/zi/advanced/ref.typ
rename to tests/zi/declare-advanced/ref.typ
index 0c94381..2a6e309 100644
--- a/tests/zi/advanced/ref.typ
+++ b/tests/zi/declare-advanced/ref.typ
@@ -6,11 +6,3 @@ $Pi^2$ \
 $"M"_dot.o\/("s"^2 th"β"^2)$ \
 $1\/("M"_dot.o th √"s"th"β"^"a")$ \
 $#sym.prime.double^2$
-
-
-#pagebreak()
-
-$"L"$ \
-$"mL"$ \
-$"l"$ \
-$"ml"$ \
diff --git a/tests/zi/advanced/test.typ b/tests/zi/declare-advanced/test.typ
similarity index 74%
rename from tests/zi/advanced/test.typ
rename to tests/zi/declare-advanced/test.typ
index 863682f..dd8ece4 100644
--- a/tests/zi/advanced/test.typ
+++ b/tests/zi/declare-advanced/test.typ
@@ -7,13 +7,3 @@
 #zi.declare($M_dot.o$, ("s", -2), ($β$, -2))() \
 #zi.declare(($M_dot.o$, -1), ("s", -0.5), ($β$, "-a"))() \
 #zi.declare((sym.prime.double, 2))() \
-
-
-#pagebreak()
-
-
-#zi.liter() \
-#zi.mL() \
-#set-unit(lowercase-liter: true)
-#zi.liter() \
-#zi.mL() \
diff --git a/tests/zi/lowercase-liter/.gitignore b/tests/zi/lowercase-liter/.gitignore
new file mode 100644
index 0000000..2e73a39
--- /dev/null
+++ b/tests/zi/lowercase-liter/.gitignore
@@ -0,0 +1 @@
+ref/
\ No newline at end of file
diff --git a/tests/zi/lowercase-liter/ref.typ b/tests/zi/lowercase-liter/ref.typ
new file mode 100644
index 0000000..9fd46fe
--- /dev/null
+++ b/tests/zi/lowercase-liter/ref.typ
@@ -0,0 +1,6 @@
+#set page(width: auto, height: auto, margin: .5em)
+
+$"L"$ \
+$"mL"$ \
+$"l"$ \
+$"ml"$ \
diff --git a/tests/zi/lowercase-liter/test.typ b/tests/zi/lowercase-liter/test.typ
new file mode 100644
index 0000000..618e36f
--- /dev/null
+++ b/tests/zi/lowercase-liter/test.typ
@@ -0,0 +1,8 @@
+#set page(width: auto, height: auto, margin: .5em)
+#import "/src/zero.typ": set-unit, zi
+
+#zi.liter() \
+#zi.mL() \
+#set-unit(lowercase-liter: true)
+#zi.liter() \
+#zi.mL() \

From e3345eea2be89a3967e021de77dbfe42f9d4b206 Mon Sep 17 00:00:00 2001
From: Mc-Zen <52877387+Mc-Zen@users.noreply.github.com>
Date: Sat, 28 Mar 2026 15:19:52 +0100
Subject: [PATCH 5/9] [move] `breakable` from unit to num

---
 README.md     | 4 ++--
 src/state.typ | 2 +-
 src/units.typ | 9 +--------
 3 files changed, 4 insertions(+), 11 deletions(-)

diff --git a/README.md b/README.md
index b848054..d4377bc 100644
--- a/README.md
+++ b/README.md
@@ -105,6 +105,7 @@ Zero's core is the `num()` function, which provides flexible number formatting.
   decimal-separator:      str = ".",
   product:                content = sym.times,
   tight:                  bool = false,
+  breakable:              bool = false,
   math:                   bool = true,
 
   omit-unity-mantissa:    bool = false,
@@ -128,6 +129,7 @@ Zero's core is the `num()` function, which provides flexible number formatting.
 - `decimal-separator: str = "."` : Specifies the marker that is used for separating integer and decimal part.
 - `product: content = sym.times` : Specifies the multiplication symbol used for scientific notation. 
 - `tight: bool = false` : If true, tight spacing is applied between operands (applies to $\times$ and $\pm$). 
+- `breakable: bool` : Whether numbers and quantities can be broken across paragraph lines. 
 - `math: bool = true` : If set to `false`, the parts of the number won't be wrapped in a `math.equation`. This makes it possible to use `num()` with non-math fonts.
 - `omit-unity-mantissa: bool = false` : Determines whether a mantissa of 1 is omitted in scientific notation, e.g., $10^4$ instead of $1\cdot 10^4$. 
 - `positive-sign: bool = false` : If set to `true`, positive coefficients are shown with a $+$ sign. 
@@ -409,7 +411,6 @@ The appearance of units can be configured via `set-unit`:
 #set-unit(
   unit-separator:  content = sym.space.thin,
   fraction:        str = "power",
-  breakable:       bool = false,
   prefix:          auto | none = auto
 )
 ```
@@ -418,7 +419,6 @@ The appearance of units can be configured via `set-unit`:
   - `"power"` : Units with negative exponents are shown as powers. 
   - `"fraction"` : When units with negative exponents are present, a fraction is created and the concerned units are put in the denominator. 
   - `"inline"` : An inline fraction is created. 
-- `breakable: bool` : Whether units and quantities can be broken across paragraph lines. 
 - `prefix: auto | none` : When set to `auto` and `num.exponent` is set to `"eng"`, a metric prefix is displayed along with the unit, replacing the exponent, e.g., `zi.m[2e4]` will render as 20km. 
 
 These options are also available when instancing a quantity, e.g., `#zi.m(fraction: "inline")[2.5]`. 
diff --git a/src/state.typ b/src/state.typ
index e0158e0..d3edcea 100644
--- a/src/state.typ
+++ b/src/state.typ
@@ -15,6 +15,7 @@
   fixed: none,
   exponent: auto,
   trim-zeros: false,
+  breakable: false,
   group: (
     size: 3,
     separator: sym.space.thin,
@@ -30,7 +31,6 @@
   unit: (
     unit-separator: sym.space.thin,
     fraction: "power",
-    breakable: false,
     use-sqrt: true,
     prefix: auto,
     lowercase-liter: false,
diff --git a/src/units.typ b/src/units.typ
index 12277dd..1be2504 100644
--- a/src/units.typ
+++ b/src/units.typ
@@ -306,7 +306,7 @@
       unit.numerator.first().first() = prefix + unit.numerator.first().first()
     }
   }
-  let breakable = utility.process-breakable(num-state.unit.breakable)
+  let breakable = utility.process-breakable(num-state.breakable)
 
   let result = {
     num(value, state: num-state, force-parentheses-around-uncertainty: true)
@@ -322,13 +322,6 @@
     )
   }
 
-  if not breakable.power {
-    if num-state.math {
-      result = box($result$)
-    } else {
-      result = box(result)
-    }
-  }
   result
 }
 

From d81fc795c951893c48245a1cffdcbe6b503107d1 Mon Sep 17 00:00:00 2001
From: Mc-Zen <52877387+Mc-Zen@users.noreply.github.com>
Date: Sat, 28 Mar 2026 19:11:19 +0100
Subject: [PATCH 6/9] [add] fine-grained breaking features

---
 src/formatting.typ | 46 ++++++++++++++++++++++++++++++++++++++--------
 src/units.typ      | 12 ++++++------
 2 files changed, 44 insertions(+), 14 deletions(-)

diff --git a/src/formatting.typ b/src/formatting.typ
index 6a2dd3a..3f16b28 100644
--- a/src/formatting.typ
+++ b/src/formatting.typ
@@ -173,9 +173,19 @@
 }
 
 
+#let nonbreaking-binary-class(body, tight: false, breakable: true) = {
+  let space = if tight { 0pt } else { 2em/9 }
+  
+  if breakable {
+    math.class("binary", body)
+  } else {
+    // Recover spacing of binary relations but without breakability
+    h(space) + math.class("normal", body) + h(space)
+  }
+}
 
 #let format-uncertainty = it => {
-  /// pm, digits, mode, concise, tight, math
+  /// pm, digits, mode, concise, tight, math, breakable
   let pm = it.pm
   if pm == none { return () }
   let is-symmetric = type(pm.first()) != array
@@ -206,18 +216,26 @@
     decimal-separator: it.decimal-separator,
   )))
   if is-symmetric {
-    if it.concise { ("(", pm.first(), ")") } else if it.math {
+    if it.concise {
+      ("(", pm.first(), ")")
+    } else if it.math {
       (
         math.class("normal", none),
-        math.class(if it.tight { "normal" } else { "binary" }, sym.plus.minus),
+        nonbreaking-binary-class(
+          sym.plus.minus, 
+          tight: it.tight, 
+          breakable: it.breakable.uncertainty
+        ),
         pm.first(),
       )
     } else {
-      let space = if not it.tight { sym.space.thin }
+      let space = if it.tight { sym.space.hair } else { sym.space.thin }
       (
         space,
+        sym.wj,
         sym.plus.minus,
         space,
+        if not it.breakable.uncertainty { sym.wj },
         pm.first(),
       )
     }
@@ -231,6 +249,7 @@
     )
   } else {
     (
+      sym.wj,
       non-math-attach(
         none,
         t: "+" + pm.at(0),
@@ -243,7 +262,7 @@
 
 
 #let format-power = it => {
-  /// x, base, product, positive-sign-exponent, tight, math
+  /// x, base, product, positive-sign-exponent, tight, math, breakable
   if it.exponent == none { return () }
 
   let (sign, integer, fractional) = decompose-signed-float-numeral(it.exponent)
@@ -262,19 +281,24 @@
     if it.product == none { (power,) } else {
       (
         box(),
-        math.class(if it.tight { "normal" } else { "binary" }, it.product),
+        nonbreaking-binary-class(
+          it.product, 
+          tight: it.tight, 
+          breakable: it.breakable.power
+        ),
         power,
       )
     }
   } else {
     let power = non-math-attach([#it.base], t: [#exponent])
     if it.product == none { (power,) } else {
-      let space = if not it.tight { sym.space.thin }
+      let space = if it.tight { sym.space.hair } else { sym.space.thin }
       (
-        box(),
         space,
+        sym.wj,
         it.product,
         space,
+        if not it.breakable.power { sym.wj },
         power,
       )
     }
@@ -284,6 +308,7 @@
 
 
 #let show-num-impl = it => {
+  let breakable = utility.process-breakable(it.breakable)
   /// sign, int, frac, e, pm,
   /// digits
   /// omit-unity-mantissa, uncertainty-mode, positive-sign
@@ -321,6 +346,7 @@
     math: it.math,
     mode: it.uncertainty-mode,
     decimal-separator: it.decimal-separator,
+    breakable: breakable
   )
 
 
@@ -332,6 +358,7 @@
     tight: it.tight,
     math: it.math,
     decimal-separator: it.decimal-separator,
+    breakable: breakable
   )
 
   let integer-part = (
@@ -349,6 +376,9 @@
   )
 
   let uncertainty-part = format-uncertainty(uncertainty)
+  if not breakable.uncertainty and uncertainty-part.len() != 0{
+    // uncertainty-part = (std.box(equation-from-items(uncertainty-part)),)
+  }
 
   if concise-uncertainty {
     fractional-part += uncertainty-part
diff --git a/src/units.typ b/src/units.typ
index 1be2504..38ec908 100644
--- a/src/units.typ
+++ b/src/units.typ
@@ -192,7 +192,7 @@
   )
 
   let fold-units = fold-units.with(
-    unit-separator: unit-separator,
+    unit-separator: unit-separator + sym.wj,
     math: math,
     use-sqrt: use-sqrt,
   )
@@ -210,7 +210,7 @@
     // Numerator could be empty!
     let result = denominator-content
     if numerator.len() != 0 {
-      result = numerator-content + unit-separator + result
+      result = numerator-content + unit-separator + sym.wj + result
     }
     return if math { $result$ } else { result }
   }
@@ -243,12 +243,12 @@
   }
   let num-state = update-num-state(num-state.get(), args)
 
-  let result = show-unit(
+  let result = (show-unit(
     unit.numerator,
     unit.denominator,
     ..num-state.unit,
     math: num-state.math,
-  )
+  ))
   result
 }
 
@@ -313,13 +313,13 @@
     sym.wj
     separator
     if not breakable.unit { sym.wj }
-    show-unit(
+    box(show-unit(
       unit.numerator,
       unit.denominator,
       fraction: num-state.unit.fraction,
       unit-separator: num-state.unit.unit-separator,
       math: num-state.math,
-    )
+    ))
   }
 
   result

From 5e7716abc02294fe673c736be561944a9c556432 Mon Sep 17 00:00:00 2001
From: Mc-Zen <52877387+Mc-Zen@users.noreply.github.com>
Date: Sun, 29 Mar 2026 21:10:32 +0200
Subject: [PATCH 7/9] [test] breaking behavior

---
 tests/breakable/.gitignore |   5 ++
 tests/breakable/ref.typ    | 113 +++++++++++++++++++++++++++++++++++++
 tests/breakable/test.typ   |  86 ++++++++++++++++++++++++++++
 tests/num/self/test.typ    |   4 +-
 4 files changed, 206 insertions(+), 2 deletions(-)
 create mode 100644 tests/breakable/.gitignore
 create mode 100644 tests/breakable/ref.typ
 create mode 100644 tests/breakable/test.typ

diff --git a/tests/breakable/.gitignore b/tests/breakable/.gitignore
new file mode 100644
index 0000000..2e4c5d8
--- /dev/null
+++ b/tests/breakable/.gitignore
@@ -0,0 +1,5 @@
+# generated by tytanic, do not edit
+
+/diff/
+/out/
+/ref/
diff --git a/tests/breakable/ref.typ b/tests/breakable/ref.typ
new file mode 100644
index 0000000..8472607
--- /dev/null
+++ b/tests/breakable/ref.typ
@@ -0,0 +1,113 @@
+#set page(width: auto, height: auto, margin: .5em)
+
+#set super(typographic: false)
+#let th = sym.space.thin
+#let hair = sym.space.hair
+
+
+== Math mode
+// Non-breakable
+#block(stroke: gray, width: 15em)[
+  The length is $(1plus.minus 2)×10^2th"m"th"s"^(-1)$.
+]
+#block(stroke: gray, width: 10em)[
+  The length is\ $(1plus.minus 2)×10^2th"m"th"s"^(-1)$.
+]
+// Single break points
+#block(stroke: gray, width: 13em)[
+  The length is $(1plus.minus 2)×10^2$\ $"m"th"s"^(-1)$.
+]
+#block(stroke: gray, width: 12em)[
+  The length is $(1plus.minus 2)×$\ $10^2th"m"th"s"^(-1)$.
+]
+#block(stroke: gray, width: 10em)[
+  The length is $(1plus.minus$\ $2)×10^2th"m"th"s"^(-1)$.
+]
+
+#pagebreak()
+
+
+== Text mode
+// Non-breakable
+#block(stroke: gray, width: 13em)[
+  The length is (1#th±#th⁠2) ⁠× ⁠10#super[2]#th;m#th;s#super[−1].
+]
+#block(stroke: gray, width: 10em)[
+  The length is\ (1#th±#th⁠2) ⁠× ⁠10#super[2]#th;m#th;s#super[−1].
+]
+// Single break points
+#block(stroke: gray, width: 11em)[
+  The length is (1#th±#th⁠2) ⁠× ⁠10#super[2]#th;\ m#th;s#super[−1].
+]
+#block(stroke: gray, width: 10.5em)[
+  The length is (1#th±#th⁠2) ⁠× \ ⁠10#super[2]#th;m#th;s#super[−1].
+]
+#block(stroke: gray, width: 10em)[
+  The length is (1#th±#th\ 2) ⁠× ⁠10#super[2]#th;m#th;s#super[−1].
+]
+
+#pagebreak()
+
+
+== Tight mode
+#block(stroke: gray, width: 14em)[
+  The length is $(1#h(0pt)plus.minus 2)#h(0pt)×#h(0pt)10^2th"m"th"s"^(-1)$.
+]
+#block(stroke: gray, width: 10em)[
+  The length is\ $(1#h(0pt)plus.minus 2)#h(0pt)×#h(0pt)10^2th"m"th"s"^(-1)$.
+]
+// Single break points
+#block(stroke: gray, width: 11em)[
+  The length is $(1#h(0pt)plus.minus 2)#h(0pt)×#h(0pt)10^2$\ $"m"th"s"^(-1)$.
+]
+#block(stroke: gray, width: 10.5em)[
+  The length is $(1#h(0pt)plus.minus 2)×$\ $10^2th"m"th"s"^(-1)$.
+]
+#block(stroke: gray, width: 10em)[
+  The length is $(1plus.minus$\ $2)#h(0pt)×#h(0pt)10^2th"m"th"s"^(-1)$.
+]
+
+
+#pagebreak()
+
+
+== Tight text mode
+#block(stroke: gray, width: 13em)[
+  The length is (1#hair±#hair⁠2)#hair;×#hair;⁠10#super[2]#th;m#th;s#super[−1].
+]
+#block(stroke: gray, width: 10em)[
+  The length is\ (1#hair±#hair⁠2)#hair;×#hair;⁠10#super[2]#th;m#th;s#super[−1].
+]
+// Single break points
+#block(stroke: gray, width: 11em)[
+  The length is (1#hair±#hair⁠2)#hair;×#hair;⁠10#super[2]#hair;\ m#th;s#super[−1].
+]
+#block(stroke: gray, width: 10.5em)[
+  The length is (1#hair±#hair⁠2)#hair;×#hair;\ ⁠10#super[2]#th;m#th;s#super[−1].
+]
+#block(stroke: gray, width: 10em)[
+  The length is (1#hair±#hair\ 2)#hair;⁠×#hair;⁠10#super[2]#th;m#th;s#super[−1].
+]
+
+
+#pagebreak()
+
+== Don't break asym. uncertainties
+#block(stroke: gray, width: 10em)[
+  The length is\
+  $\(1#none^(+2)_(-2))×10^2th"m"$.
+]
+#block(stroke: gray, width: 10em)[
+  The length is \
+  #import "/src/zero.typ": zi
+  #zi.meter("1+2-2e2", math: false).
+]
+
+#pagebreak()
+
+#set page(width: 9em, height: auto, margin: .5em)
+
+
+Unit of force is $"kg"th"m"th"stel"th"A"th"A"th"s"^(-2)th"mol"^(-1)$ 
+
+Unit of force is \ #box(width: 10cm)[kg#th;m#th;stel#th;A#th;A#th;s#super[−2]#th;mol#super[−1]] \
\ No newline at end of file
diff --git a/tests/breakable/test.typ b/tests/breakable/test.typ
new file mode 100644
index 0000000..f25933c
--- /dev/null
+++ b/tests/breakable/test.typ
@@ -0,0 +1,86 @@
+#import "/src/zero.typ": *
+
+// #set box(fill: red)
+#set page(width: auto, height: auto, margin: .5em)
+
+#let test-clause(..args) = [
+  #[The length is] #(zi.m-s("1+-2e2", ..args)). \
+  // #hide[The length is] #(zi.meter("1+2-2e2", ..args)).
+]
+
+== Math mode
+// Non-breakable
+#block(stroke: gray, width: 15em, test-clause())
+#block(stroke: gray, width: 10em, test-clause())
+// Single break points
+#block(stroke: gray, width: 13em, test-clause(breakable: (unit: true)))
+#block(stroke: gray, width: 12em, test-clause(breakable: (power: true)))
+#block(stroke: gray, width: 10em, test-clause(breakable: (uncertainty: true)))
+
+#pagebreak()
+
+
+== Text mode
+#set-num(math: false)
+#block(stroke: gray, width: 13em, test-clause())
+#block(stroke: gray, width: 10em, test-clause())
+// Single break points
+#block(stroke: gray, width: 11em, test-clause(breakable: (unit: true)))
+#block(stroke: gray, width: 10.5em, test-clause(breakable: (power: true)))
+#block(stroke: gray, width: 10em, test-clause(breakable: (uncertainty: true)))
+
+#pagebreak()
+
+
+== Tight mode
+#set-num(tight: true, math: true)
+#block(stroke: gray, width: 14em, test-clause())
+#block(stroke: gray, width: 10em, test-clause())
+// Single break points
+#block(stroke: gray, width: 11em, test-clause(breakable: (unit: true)))
+#block(stroke: gray, width: 10.5em, test-clause(breakable: (power: true)))
+#block(stroke: gray, width: 10em, test-clause(breakable: (uncertainty: true)))
+
+
+#pagebreak()
+
+
+== Tight text mode
+#set-num(tight: true, math: false)
+#block(stroke: gray, width: 13em, test-clause())
+#block(stroke: gray, width: 10em, test-clause())
+// Single break points
+#block(stroke: gray, width: 11em, test-clause(breakable: (unit: true)))
+#block(stroke: gray, width: 10.5em, test-clause(breakable: (power: true)))
+#block(stroke: gray, width: 10em, test-clause(breakable: (uncertainty: true)))
+
+
+#pagebreak()
+
+== Don't break asym. uncertainties
+#set-num(tight: false, math: true)
+#block(stroke: gray, width: 10em)[
+  The length is #(zi.meter("1+2-2e2", breakable: (uncertainty: true))).
+]
+#set-num(tight: false, math: false)
+#block(stroke: gray, width: 10em)[
+  The length is #(zi.meter("1+2-2e2", breakable: (uncertainty: true))).
+]
+
+#pagebreak()
+
+
+
+#set page(width: 9em, height: auto, margin: .5em)
+
+#set-num(tight: false, math: true)
+
+
+#let long-unit = zi.declare("kg m/s^2/mol/N stel A A")
+
+
+#set-num(breakable: false)
+Unit of force is #long-unit(). 
+
+#set-num(math: false)
+Unit of force is #long-unit(). 
diff --git a/tests/num/self/test.typ b/tests/num/self/test.typ
index 905443f..6ea50c8 100644
--- a/tests/num/self/test.typ
+++ b/tests/num/self/test.typ
@@ -290,7 +290,7 @@
 // num with manual state
 
 #[
-  #let state = default-state
+  #let state = impl.default-state
   #{ state.decimal-separator = "," }
   #let num = num.with(state: state)
   #num[2.34]
@@ -309,7 +309,7 @@
 // num with state input
 
 #context {
-  let state = num-state.get()
+  let state = impl.num-state.get()
   num("1", state: state)
   [ ]
   num("2", state: state)

From 90563ddaea134bb178281e765a8dd82e5eca04a1 Mon Sep 17 00:00:00 2001
From: Mc-Zen <52877387+Mc-Zen@users.noreply.github.com>
Date: Sun, 29 Mar 2026 21:12:23 +0200
Subject: [PATCH 8/9] [revert] move of state to impl

---
 tests/num/self/test.typ | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tests/num/self/test.typ b/tests/num/self/test.typ
index 6ea50c8..905443f 100644
--- a/tests/num/self/test.typ
+++ b/tests/num/self/test.typ
@@ -290,7 +290,7 @@
 // num with manual state
 
 #[
-  #let state = impl.default-state
+  #let state = default-state
   #{ state.decimal-separator = "," }
   #let num = num.with(state: state)
   #num[2.34]
@@ -309,7 +309,7 @@
 // num with state input
 
 #context {
-  let state = impl.num-state.get()
+  let state = num-state.get()
   num("1", state: state)
   [ ]
   num("2", state: state)

From 24e2e40acac89801ad5a14d8fc97927cbfbee148 Mon Sep 17 00:00:00 2001
From: Mc-Zen <52877387+Mc-Zen@users.noreply.github.com>
Date: Sun, 29 Mar 2026 21:17:11 +0200
Subject: [PATCH 9/9] [docs] for `breakable`

---
 README.md | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index d4377bc..de3d1fb 100644
--- a/README.md
+++ b/README.md
@@ -105,7 +105,7 @@ Zero's core is the `num()` function, which provides flexible number formatting.
   decimal-separator:      str = ".",
   product:                content = sym.times,
   tight:                  bool = false,
-  breakable:              bool = false,
+  breakable:              bool | dict = false,
   math:                   bool = true,
 
   omit-unity-mantissa:    bool = false,
@@ -129,7 +129,7 @@ Zero's core is the `num()` function, which provides flexible number formatting.
 - `decimal-separator: str = "."` : Specifies the marker that is used for separating integer and decimal part.
 - `product: content = sym.times` : Specifies the multiplication symbol used for scientific notation. 
 - `tight: bool = false` : If true, tight spacing is applied between operands (applies to $\times$ and $\pm$). 
-- `breakable: bool` : Whether numbers and quantities can be broken across paragraph lines. 
+- `breakable: bool | dict` : Whether numbers and quantities can be broken across paragraph lines. Setting this to `true`/`false` entirely enables/disables breaking. For more fine-grained control, a dictionary with the keys `uncertainty`, `power`, and `unit` (all booleans) can be passed for specifying whether breaks are allowed after the ± symbol, the × symbol, or before the unit, respectively. 
 - `math: bool = true` : If set to `false`, the parts of the number won't be wrapped in a `math.equation`. This makes it possible to use `num()` with non-math fonts.
 - `omit-unity-mantissa: bool = false` : Determines whether a mantissa of 1 is omitted in scientific notation, e.g., $10^4$ instead of $1\cdot 10^4$. 
 - `positive-sign: bool = false` : If set to `true`, positive coefficients are shown with a $+$ sign.