--- /dev/null
+# unit-case
+
+Specify lowercase or uppercase for units.
+
+```css
+ a { width: 10px; }
+/** ↑
+ * These units */
+```
+
+## Options
+
+`string`: `"lower"|"upper"`
+
+### `"lower"`
+
+The following patterns are considered violations:
+
+```css
+a {
+ width: 10PX;
+}
+```
+
+```css
+a {
+ width: 10Px;
+}
+```
+
+```css
+a {
+ width: 10pX;
+}
+```
+
+```css
+a {
+ width: 10PIXEL;
+}
+```
+
+```css
+a {
+ width: calc(10PX * 2);
+}
+```
+
+The following patterns are *not* considered violations:
+
+```css
+a {
+ width: 10px;
+}
+```
+
+```css
+a {
+ width: calc(10px * 2);
+}
+```
+
+### `"upper"`
+
+The following patterns are considered violations:
+
+```css
+a {
+ width: 10px;
+}
+```
+
+```css
+a {
+ width: 10Px;
+}
+```
+
+```css
+a {
+ width: 10pX;
+}
+```
+
+```css
+a {
+ width: 10pixel;
+}
+```
+
+```css
+a {
+ width: calc(10px * 2);
+}
+```
+
+The following patterns are *not* considered violations:
+
+```css
+a {
+ width: 10PX;
+}
+```
+
+```css
+a {
+ width: calc(10PX * 2);
+}
+```