Most characters you type is concerned with inline-structured elements. The content of a zettel contains is many cases just ordinary text, lightly formatted. Inline-structured elements allow to format your text and add some helpful links or images. Sometimes, you want to enter characters that have no representation on your keyboard.
Every text formatting element begins with two same characters at the beginning. It lasts until the same two characters occurred the second time. Some of these elements explicitly support attributes.
Sometime you want to enter the text as it is.
This is the core motivation of literal-like formatting.
You can reference other zettel and (external) material within one zettel. This kind of reference may be a link, or an images that is display inline when the zettel is rendered. Footnotes sometimes factor out some useful text that hinders the flow of reading text. Internal marks allow to reference something within a zettel. An important aspect of all knowledge work is to reference others work, e.g. with citation keys. All these elements can be subsumed under reference-like text.
A comment begins with two consecutive percent sign characters (“%”, U+0025). It ends at the end of the line where it begins.
The backslash character (“\”, U+005C) gives the next character another meaning.
Sometimes it is not easy to enter special characters. If you know the Unicode code point of that character, or its name according to the HTML standard, you can enter it by number or by name.
Regardless which method you use, an entity always begins with an ampersand character (“&”, U+0026) and ends with a semicolon character (“;”, U+003B). If you know the HTML name of the character you want to enter, put it between these two character. Example: & is rendered as &.
If you want to enter its numeric code point, a number sign character must follow the ampersand character, followed by digits to base 10. Example: & is rendered in HTML as &.
You also can enter its numeric code point as a hex number, if you put the letter “x” after the numeric sign character. Example: & is rendered in HTML as &.
According to the HTML Standard, some numeric code points are not allowed. These are all code point below the numeric value 32 (decimal) or 0x20 (hex) and all code points for noncharacter values.
Since some Unicode character are used quite often, a special notation is introduced for them:
pages 4--7 will be rendered in HTML as: pages 4–7. Alternative specifications are: –, &x8211, and –.