--- /dev/null
+# function-parentheses-newline-inside
+
+Require a newline or disallow whitespace on the inside of the parentheses of functions.
+
+```css
+ a {
+ transform: translate(
+ 1, /* ↑ */
+ 1 /* ↑ */
+ ); /* ↑ */
+ } /* ↑ */
+/** ↑ ↑
+ * The newline inside these two parentheses */
+```
+
+## Options
+
+`string`: `"always"|"always-multi-line"|"never-multi-line"`
+
+### `"always"`
+
+There *must always* be a newline inside the parentheses.
+
+The following patterns are considered violations:
+
+```css
+a { transform: translate(1, 1); }
+```
+
+```css
+a { transform: translate(1,
+ 1
+ ); }
+```
+
+The following patterns are *not* considered violations:
+
+```css
+a {
+ transform: translate(
+ 1, 1
+ );
+}
+```
+
+```css
+a {
+ transform: translate(
+ 1,
+ 1
+ );
+}
+```
+
+### `"always-multi-line"`
+
+There *must always* be a newline inside the parentheses of multi-line functions.
+
+The following patterns are considered violations:
+
+```css
+a { transform: translate(1,
+ 1) }
+```
+
+The following patterns are *not* considered violations:
+
+```css
+a { transform: translate(1, 1) }
+```
+
+```css
+a { transform: translate( 1, 1 ) }
+```
+
+```css
+a {
+ transform: translate(
+ 1, 1
+ );
+}
+```
+
+```css
+a {
+ transform: translate(
+ 1,
+ 1
+ );
+}
+```
+
+### `"never-multi-line"`
+
+The following patterns are considered violations:
+
+```css
+a {
+ transform: translate(
+ 1, 1
+ );
+}
+```
+
+```css
+a {
+ transform: translate(
+ 1,
+ 1
+ );
+}
+```
+
+The following patterns are *not* considered violations:
+
+```css
+a { transform: translate(1, 1) }
+```
+
+```css
+a { transform: translate( 1, 1 ) }
+```
+
+```css
+a { transform: translate(1,
+ 1) }
+```