19. Simple, fast, purely declarative counters
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## 19. Simple, fast, purely declarative counters

Standard CSS counters, that is `counter-reset`, `counter-increment`, `counter()` and `counters()`, are fully supported by XXE. However, for most uses, we also have a simpler, faster because purely declarative, alternative to standard CSS counters.

Proprietary `simple-counter()` and `simple-counters()` may be used everywhere you use `counter()` and `counters()` and this, with a similar syntax: `simple-counters(n, ".")`, `simple-counter(n, upper-roman)`, etc. But, being purely declarative, you don't need to specify `simple-counter-reset` or `simple-counter-increment` in order to declare and update them.

Just like `counter` and `counters`, `simple-counter` and `simple-counters` are supported inside the `content` property. However their semantics are very different: the name of the counter specifies the non-formatted value of the counter.

Example 1 (XHTML):

    ol > li:before {
        display: marker;
        content: simple-counter(n, decimal);
        font-weight: bold;
    }

In the previous example, the counter name is `n` (single letter 'n', any letter is OK) which specifies that the counter value is the rank of `li` within its parent element (an `ol`).

Example 2 (DocBook):

    sect3 > title:before {
        content: simple-counter(nnn-) " ";
    }

In the previous example, the counter name is `nnn-` (3 letters followed by a dash) which specifies that the counter segmented value must be built as follows:

1. Skip (dash means skip) the rank of `title` within its parent element (a `sect3`).

2. Prepend (any letter means use) the rank of `title` parent (a `sect3`) within its parent (a `sect2`).

3. Prepend the rank of `title` grand-parent (a `sect2`) within its parent (a `sect1`).

4. Prepend the rank of `title` grand-grand-parent (a `sect1`) within its parent (an `article` or a `chapter`).

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