# rule

## Description
A rule is a sequence of actions that can be shared by multiple regulators in
the config file.  Rules define a standard way to perform an operation.  Rules
are used to minimize duplication in the config file.

For example, the following action sequences might be sharable using a rule:
* Actions that set the output voltage of a regulator rail
* Actions that read all the sensors of a regulator rail
* Actions that detect down-level hardware using version registers
* Actions that detect phase faults

## Properties
| Name | Required | Type | Description |
| :--- | :------: | :--- | :---------- |
| comments | no | array of strings | One or more comment lines describing this rule. |
| id | yes | string | Unique ID for this rule.  Can only contain letters (A-Z, a-z), numbers (0-9), and underscore (\_). |
| actions | yes | array of [actions](action.md) | One or more actions to execute. |

## Return Value
Return value of the last action in the "actions" property.

## Example
```
{
  "comments": [ "Sets output voltage of PAGE 0 of a PMBus regulator" ],
  "id": "set_page0_voltage_rule",
  "actions": [
    { "i2c_write_byte": { "register": "0x00", "value": "0x00" } },
    { "pmbus_write_vout_command": { "format": "linear" } }
  ]
}

... later in the config file ...

"configuration": {
  "volts": 1.03,
  "rule_id": "set_page0_voltage_rule"
}
```