System Constants

Thirteen values are available in any template of any module — there is no need to pass them via TplAssign, they are substituted by the platform automatically.

They can be transformed with modifiers and compared in conditions. There is no need to pass them via TplAssign, but in a template they behave like regular variables: {TEMPLATE|upper} will apply a modifier, and {*TEMPLATE==mobi} … {TEMPLATE*} will show a block only for the required group. They are substituted late — on the finished output of the module (see “When Substitution Occurs”).

Paths and Styling

Tag	Value
`{ROOT}`	base path of the site
`{PATH}`	path to the current template group, same as `{ROOT}templates/{TEMPLATE}`
`{TEMPLATE}`	name of the current template group
`{MELBIS_COPY}`	ready-made “Powered by Melbis Shop” link with version number

<link rel="stylesheet" href="{PATH}/statics/bundle.base.css">
<img src="{PATH}/images/design/logo.png">

{PATH} is the most frequently used of all: every link to a static asset, image, or bundle is built from it, and when the template group is switched, the paths update automatically.

Language and Locale

Tag	Value
`{LANG}`	current page language
`{CHARSET}`	project encoding
`{TIME_ZONE}`	project time zone

<html lang="{LANG}">
<meta charset="{CHARSET}">

The language and template group can be switched from code — using the LanguageSet and TemplateSet methods before calling Run (see “Template Groups”).

Visitor Session

Tag	Value
`{CSRF_TOKEN}`	form protection token
`{PHP_SESS_ID}`	visitor session identifier

<form method="post" action="/order/">
    <input type="hidden" name="csrf" value="{CSRF_TOKEN}">
</form>

If Hasn't session is displayed instead of a value, it means DefineSession has not been called in the root script — see “Sessions and CSRF”.

Versions and Cache

Tag	Value
`{BUILD}`	project build number — the `MELBIS_BUILD` parameter from `config.json`
`{SCRIPT_VERSION}` / `{SCRIPT_BUILD}`	engine version and build, defined within the platform itself
`{LAST_MODIFY}`	date of the last page cache update in HTTP format

It is important to clearly distinguish the first two: {BUILD} is your project — it increments when files are saved in the development environment and serves as a static asset version marker; {SCRIPT_*} is the version of the Melbis Shop engine itself and has nothing to do with your code.

<script defer src="{PATH}/statics/bundle.melbis.js?{BUILD}"></script>

As long as the number has not changed, the browser loads the file from its own cache; once it increases, the file is downloaded again. For more details, see “Static Asset Build”.

When Substitution Occurs

System tags are resolved late — on the finished output of the module, after the cache and after the module’s own data has been parsed. This has practical implications:

They work everywhere — including inside blocks coming from the cache and inside values assembled by other templates.
The value is always current for the present request: language, group, and session token are taken “here and now”, rather than being baked into the module cache.
On this same late pass, modifiers ({LANG|upper}) and conditions ({*TEMPLATE==mobi} … {TEMPLATE*}) are applied to them.
The downside of late parsing: inside a condition based on a system tag, only system and global values are visible, but not local module variables — the module has already finished executing by that point. For blocks with row data, use regular conditions based on passed variables.

The Service Tag `{NULL}`

{NULL} stands apart — it is a reserved tag available in any template regardless of what data the module has passed. On its own it always outputs an empty string and serves as a “carrier” for modifiers that do not require a variable value: this allows a modifier to be applied to static parameters rather than to data from the database (see the example with a static file in the |webp modifier section under “Modifiers”).

{NULL} is a regular template engine tag: empty on its own, but modifiers work on it — that is precisely why it exists.