Arbital Markdown

The Ar­bital ed­i­tor uses Mark­down syn­tax for edit­ing the pages. If you’ve used Red­dit or any of the Stack­Overflow, it’s the same syn­tax. Here is a helpful in­tro to Mark­down syn­tax.

Ar­bital Mark­down syntax

Ar­bital adds a few ex­tra fea­tures to Mark­down syn­tax.

Table of contents

`` cre­ates a table of con­tents, like the one above.


Add note about the In­tr­a­site Link but­ton on the toolbar.

You can quickly link to a page by us­ing id or, even bet­ter, alias syn­tax. For ex­am­ple:
Ar­bital Mark­downAr­bital Mark­down
Ar­bital mark­downAr­bital Markdown

If you want the in­serted ti­tle to be lower-cased, add a dash:
value al­ign­ment prob­lemValue al­ign­ment prob­lem
value al­ign­ment prob­lemvalue al­ign­ment problem

If you want to spec­ify what text shows up as the link, use text. For ex­am­ple:
Cus­tom linkCus­tom link

If you link to a page that doesn’t ex­ist, the link will show up red:
Doesn’t ex­istDoesn’t exist

If you want to just cre­ate a red link with some text:
cre­ate a page for this con­cept latercre­ate a page for this con­cept later

If you want to men­tion some­one use @userId or @userAlias:
NOTE: the user will get an up­date if the men­tion is in a com­ment. <div><div>


You can set the page’s sum­mary, which shows up in green­link popovers and other places. For ex­am­ple:
Sum­mary of the page goes here. *Mark­down* is okay!
Or to set a spe­cific sum­mary:
Very tech­ni­cal sum­mary. *Mark­down* is okay!
Make sure that the en­tire sum­mary block is in a para­graph of its own.

Hid­den text

You can cre­ate hid­den text:

Hid­den text goes here.


You can use this for hid­ing prob­lem an­swers and ask­ing the user to solve the prob­lem them­selves be­fore click­ing the but­ton to see the cor­rect an­swer. But­ton text is re­quired.


You can cre­ate notes, which are snip­pets of text hid­den be­hind a ques­tion mark. You can put foot­notes or other text that might be in­ter­est­ing to some users, but not to ev­ery­one. For ex­am­ple:
noteFun note text! will show up as: noteFun note text!

com­ment: Alexei An­dreev: this is not some­thing we want to ad­ver­tise at this time.
You can em­bed votes from other pages. For ex­am­ple:
3r cre­ates this vot­ing bar:

To­dos, com­ments, and fixmes

You can leave todo mark­ers for your­self or other au­thors. For ex­am­ple:
finish this sec­tion finish this sec­tion

todo: You can put any funky *mark­down* syn­tax here in­clud­ing `links`.

This will only ap­pear in the top qual­ity bar when ex­panded, not the page text. Red links and “todo” mark­ers count to­wards the todo score, which you will see next to the pages on the Ex­plore and your Pro­file pages.
todo: You can put any funky mark­down syn­tax here in­clud­ing links.

Similarly, you can leave com­ments or fixmes for other au­thors, but with­out in­creas­ing the todo count. For ex­am­ple:
there has got to be a bet­ter metaphor for this this needs to be fixed, but I’ve got it there has got to be a bet­ter metaphor for this this needs to be fixed, but I’ve got it

com­ment: You can put any funky *mark­down* syn­tax here. You can vary the num­ber of %s to en­velop other similar blocks.

Again, this doesn’t show up for the reader in any way.

com­ment: You can put any funky mark­down syn­tax here. You can vary the num­ber of %s to en­velop other similar blocks.

ques­tions and path generation

con­di­tional text


If you’re new to LaTeX you may want to read the Wik­i­books guide

You can use $ to cre­ate in­line math­e­mat­i­cal ex­pres­sions, e.g.\(ax^2 + bx + c = 0\) will be dis­played as: \(ax^2 + bx + c = 0\)
And $$ to cre­ate cen­tered math ex­pres­sions, e.g.

$$\lim_{N \to \infty} \sum_{k=1}^N f(t_k) \Delta t$$
will be dis­played as:
$$\lim_{N \to \infty} \sum_{k=1}^N f(t_k) \Delta t$$

The ed­i­tor can get a lit­tle slow if you are edit­ing very LaTeX-heavy pages. If this is an is­sue for you, let us know, and in the mean­time you can dis­able MathJax on the set­tings page.