# function-allowed-list Specify a list of allowed functions. ```css a { transform: scale(1); } /** ↑ * This function */ ``` The [`message` secondary option](../../../docs/user-guide/configure.md#message) can accept the arguments of this rule. ## Options `array|string|regex`: `["array", "of", "unprefixed", /functions/, "/regex/"]|"function"|"/regex/"|/regex/` If a string is surrounded with `"/"` (e.g. `"/^rgb/"`), it is interpreted as a regular expression. Given: ```json ["scale", "rgba", "/linear-gradient/"] ``` The following patterns are considered problems: ```css a { transform: rotate(1); } ``` ```css a { color: hsla(170, 50%, 45%, 1) } ``` ```css a { background: red, -webkit-radial-gradient(red, green, blue); } ``` The following patterns are _not_ considered problems: ```css a { background: red; } ``` ```css a { transform: scale(1); } ``` ```css a { color: rgba(0, 0, 0, 0.5); } ``` ```css a { background: red, -moz-linear-gradient(45deg, blue, red); } ```