${DynamicText("About this genre (loading...)")}
	
The original japanese name "サントイッチ - santoitchi" is a wordplay on "サンドイッチ sandwich" and "サントイチ three and one".

Although this genre has been referred to as "Sandwich", page.author wishes it be named "Trizone" in English, to preserve the wordplay. This name was chosen by page.author as an English word also containing "three" and "one", with a thematic bonus of being an historical term about "region division".


## page.title puzzles

###page.author
W=4x4&L=(2)2(4)5(1)1(3)5&T=Example&G=trizone
W=6x6&L=(1)0(2)3(2)2(1)6(2)3(3)6(2)5(3)3(1)2(2)3&G=trizone
W=7x7&L=(3)2(2)1(2)4(1)5(3)1(3)4(2)6(2)6(2)2(2)3(3)5(3)3(2)6&G=trizone
W=8x8&L=(3)3(1)4(2)3(1)2(2)2(3)2(1)5(2)5(3)2(2)3(4)2(3)11(3)3(1)3(3)6(2)4(1)3&G=trizone
W=9x9&L=(2)0(2)6(2)4(1)2(3)2(3)3(3)3(3)4(2)3(2)7(6)6(1)2(2)11(3)1(4)3(3)3(3)4(2)4(3)3(1)4(1)3&G=trizone
((U=http://www.inabapuzzle.com/honkaku/san.pdf))
((authored))


### site.author

W=5x5&LF=z13z4z4z3&L=(0)2(1)2(2)3(2)2(0)2(2)5(4)7&SSE=3RRULU3U3DDRURDD11U2RU&T=example&D=02/07/2023&G=trizone
W=9x7&LF=z13z28z6z4z2z6&L=y4y4y1y1y5y2y1y3y1y4y3y1y1y1y10y3y11y5y1&SSE=2RRDLD10UURDD2U10U5UU4RRD1RRRDL3URU9RDRDRD5UULDL3RRR8DRDR2UULULLLDDLULUURURDDLLLUL2UR&T=The_real_questions&D=04-11-2023&F=3&G=trizone
((sited))

### @AnuragSahay

#### Classic

W=7x7&L=x0x1x1x1x1x1x1x1x1x3x1x1x1(0)1x4x1(1)3(1)1x3x1(0)1(3)3x1x1x1x1x3x1x1x1x1x1x1x1x1x1&G=trizone&A=Anurag_sahay&D=2024-02-26&F=1&T=The_“odds”_are_against_symmetry
W=5x5&L=(2)0(0)4(2)6(2)3(2)1(1)6(2)1&G=trizone&A=Anurag_Sahay&D=2024-02-28&F=2
W=5x6&L=(2)0(2)5(3)4x2(2)1x4(0)1x4(2)3(2)4x1&G=trizone&A=Anurag_sahay&D=2024-02-29&F=2&T=Wasteland
W=6x6&L=x0(1)3(1)1(1)1(0)8(1)1y6(2)1y9y1y1(1)3&G=trizone&A=Anurag_sahay&D=2024-03-02&F=2&T=Quite_the_Trio

#### hex

V=hex

Using the ´´hex´´ variant:
W=4x4x4&L=x0x1x2(2)1(1)1(2)1x3(3)2x5(1)3(0)4(1)2(0)2x3(1)4x2&V=hex&G=trizone&A=Anurag_Sahay&D=2024-03-01&F=2



### @Pinkhoodie

W=7x12&LF=z0z7z4z5z13z5z8z2z4z9z7z8z2z6z2&L=(1)14(1)1(2)2(1)2(1)2(2)1(1)3(2)2(3)3(2)1(3)2(1)16(0)2(3)2(3)1(1)4(3)3(1)1(2)1(1)3(1)1(3)2(1)1&SSE=4RRDLDL2RR1RR4RDRDLL2URURDD15U8URU6UULD6R2RD10LULDDRD6UR1LLURR2LUL3UULDDDRURDR1RR1U7LUUU1UR4U15LLUU&G=trizone&A=PinkHoodie&D=2024-03-01&F=2&O=Enigmarch_2024&T=Beaten_Door


## Acknowledgements and Changes

Thanks to @bakpao, @Iori, @Wand125 and page.author for discussion that eventually settled the genre's English name.

**2023-06-28** Thanks to @MartinEnder for help clarifying the rules and other aspects of this page, as well as requesting empty-tile marks and auto-borders around shaded cells
**2023-06-29** Thanks to @Bakpao for surfacing that empty crossed regions shouldn't be highlighted / undivided region outlines should be subtler
**2023-11-04** Fixed a regression found by @Solyu (lines can be drawn starting at the outer frame again)
**2023-11-04** Question marks were added, a variant by @PinkHoodie; and a new harder puzzle was included!
**2024-01-17** A recent regression (yesterday) found by @placeholder and @pinkhoodie was corrected - thank you! 
**2024-02-26** @AnuragSahay sent a classic 7x7 - thank you!
**2024-02-28** The rule panels of [Trizone] were masterfully [modernised|kudamono/panels#modern] by @AnuragSahay, who sent a second, classic puzzle - thank you!
**2024-02-26** @AnuragSahay made a third classic [Trizone] - thank you!
**2024-03-02** @PinkHoodie and @AnuragSahay sent ean a [Trizone] - thank you!
**2024-03-04** @Anurag sent a ´´hex ´´´ variant puzzle!