The core of a ENiGMA½ based BBS is `menu.hjson`. Note that when `menu.hjson` is referenced, we're actually talking about `config/yourboardname-menu.hjson` or similar. This file determines the menus (or screens) a user can see, the order they come in and how they interact with each other, ACS configuration, etc. Like all configuration within ENiGMA½, menu configuration is done in [HJSON](https://hjson.org/) format. See [HJSON General Information](hjson.md) for more information.
Entries in `menu.hjson` are often referred to as *blocks* or *sections*. Each entry defines a menu. A menu in this sense is something the user can see or visit. Examples include but are not limited to:
Menu entries live under the `menus` section of `menu.hjson`. The *key* for a menu is it's name that can be referenced by other menus and areas of the system.
Below is a table of **common** menu entry members. These members apply to most entries, though entries that are backed by a specialized module (ie: `module: bbs_list`) may differ. See documentation for the module in question for particulars.
| Item | Description |
|--------|--------------|
| `desc` | A friendly description that can be found in places such as "Who's Online" or wherever the `%MD` MCI code is used. |
| `next` | Specifies the next menu entry to go to next. Can be explicit or an array of possibilities dependent on ACS. See **Flow Control** in the **ACS Checks** section below. If `next` is not supplied, the next menu is this menus parent. |
A given menu entry is backed by a *menu module*. That is, the code behind it. Menus are considered "standard" if the `module` member is not specified (and therefore backed by `core/standard_menu.js`).
See [Menu Modules](/docs/modding/menu-modules.md) for more information.
The `menuFlags` field of a `config` block can change default behavior of a particular menu.
| Flag | Description |
|------|-------------|
| `noHistory` | Prevents the menu from remaining in the menu stack / history. When this flag is set, when the **next** menu falls back, this menu will be skipped and the previous menu again displayed instead. Example: menuA -> menuB(noHistory) -> menuC: Exiting menuC returns the user to menuA. |
| `popParent` | When *this* menu is exited, fall back beyond the parent as well. Often used in combination with `noHistory`. |
| `forwardArgs` | If set, when the next menu is entered, forward any `extraArgs` arguments to *this* menu on to it. |
ENiGMA½ uses a concept of *forms* in menus. A form is a collection of associated *views*. Consider a New User Application using the `nua` module: The default implementation utilizes a single form with multiple EditTextView views, a submit button, etc. Forms are identified by number starting with `0`. A given menu may have mutiple forms (often associated with different states or screens within the menu).
Menus may also support more than one layout type by using a *MCI key*. A MCI key is a alpha-numerically sorted key made from 1:n MCI codes. This lets the system choose the appropriate set of form(s) based on theme or random art. An example of this may be a matrix menu: Perhaps one style of your matrix uses a vertical light bar (`VM` key) while another uses a horizontal (`HM` key). The system can discover the correct form to use by matching MCI codes found in the art to that of the available forms defined in `menu.hjson`.
When a form is submitted, it's data is matched against a *submit handler*. When a match is found, it's *action* is performed.
### Submit Actions
Submit actions are declared using the `action` member of a submit handler block. Actions can be kick off system/global or local-to-module methods, launch other menus, etc.
| Action | Description |
|--------|-------------|
| `@menu:menuName` | Takes the user to the *menuName* menu |
| `@systemMethod:methodName` | Executes the system/global method *methodName*. See **System Methods** below. |
| `@method:methodName` | Executes *methodName* local to the calling module. That is, the module set by the `module` member of a menu entry. |
| `@method:/path/to/some_module.js:methodName` | Executes *methodName* exported by the module at */path/to/some_module.js*. |
#### Method Signature
Methods executed using `@method`, or `@systemMethod` have the following signature:
```
(callingMenu, formData, extraArgs, callback)
```
#### System Methods
Many built in global/system methods exist. Below are a few. See [system_menu_method](/core/system_menu_method.js) for more information.
The above entry `telnetConnected` is set as the Telnet server's first menu entry (set by `firstMenu` in the Telnet server's config). The entry sets up a few things:
In the above entry, you'll notice `form`. This defines a form(s) object. In this case, a single form by ID of `0`. The system is then told to use a block only when the resulting art provides a `VM` (*VerticalMenuView*) MCI entry. Some other bits about the form:
*`VM1` is then setup to `submit` and start focused via `focus: true` as well as have some menu entries ("login", "apply", ...) defined. We provide an `argName` of `matrixSubmit` for this element view.
* The `submit` object tells the system to attempt to apply provided match entries from any view ID (`*`).
* Upon submit, the first match will be executed. For example, if the user selects "login", the first entry with a value of `{ matrixSubmit: 0 }` will match (due to 0 being the first index in the list and `matrixSubmit` being the arg name in question) causing `action` of `@menu:login` to be executed (go to `login` menu).
Menu modules can check user ACS in order to restrict areas and perform flow control. See [ACS](acs.md) for available ACS syntax.
### Menu Access
To restrict menu access add an `acs` key to `config`. Example:
```
opOnlyMenu: {
desc: Ops Only!
config: {
acs: ID1
}
}
```
### Flow Control
The `next` member of a menu may be an array of objects containing an `acs` check as well as the destination. Depending on the current user's ACS, the system will pick the appropriate target. The last element in an array without an `acs` can be used as a catch all. Example:
