diff --git a/accessibility-checker-engine/src/v2/checker/accessibility/util/legacy.ts b/accessibility-checker-engine/src/v2/checker/accessibility/util/legacy.ts
index 9b78b05c0..8e396b82c 100644
--- a/accessibility-checker-engine/src/v2/checker/accessibility/util/legacy.ts
+++ b/accessibility-checker-engine/src/v2/checker/accessibility/util/legacy.ts
@@ -436,7 +436,45 @@ export class RPTUtil {
         if (!allowedRoles && allowedRoles.length === 0)
             return false;
     
-        const parent = element.parentElement;
+        let parent = element.parentElement;
+        // datalist, fieldset, optgroup, etc. may be just used for grouping purpose, so go up to the parent
+        while (parent && roles.some(role => role === 'group'))
+            parent = parent.parentElement;
+         
+        if (parent && (parent.hasAttribute("tabindex") || RPTUtil.isTabbable(parent))) {
+            const target_roles =["listitem", "menuitem", "menuitemcheckbox", "menuitemradio", "option", "radio", "switch", "treeitem"];
+            if (allowedRoles.includes('any') || roles.some(role => target_roles.includes(role)))
+                return true;
+        }
+        return false;
+    }
+
+    /**
+     * an "inline" CSS display property tells the element to fit itself on the same line. An 'inline' element's width and height are ignored. 
+     * some element has default inline property, such as <span>, <a>, <img>
+     * most formatting elements inherent inline property, such as <em>, <strong>, <i>, <small> 
+     * an "inline-block" element still place element in the same line without breaking the line, but the element's width and height are applied. 
+     */
+    public static isInline(element) {
+        if (!element) return false;
+        
+        const inline_elements = ["listitem", "menuitem", "menuitemcheckbox", "menuitemradio", "option", "radio", "switch", "treeitem"];
+        if (element.hasAttribute("tabindex") || RPTUtil.isTabbable(element)) return true;
+        
+        const roles = RPTUtil.getRoles(element, true); 
+        if (!roles && roles.length === 0)
+            return false;
+
+        let tagProperty = RPTUtil.getElementAriaProperty(element);
+        let allowedRoles = RPTUtil.getAllowedAriaRoles(element, tagProperty);
+        if (!allowedRoles && allowedRoles.length === 0)
+            return false;
+    
+        let parent = element.parentElement;
+        // datalist, fieldset, optgroup, etc. may be just used for grouping purpose, so go up to the parent
+        while (parent && roles.some(role => role === 'group'))
+            parent = parent.parentElement;
+         
         if (parent && (parent.hasAttribute("tabindex") || RPTUtil.isTabbable(parent))) {
             const target_roles =["listitem", "menuitem", "menuitemcheckbox", "menuitemradio", "option", "radio", "switch", "treeitem"];
             if (allowedRoles.includes('any') || roles.some(role => target_roles.includes(role)))
diff --git a/accessibility-checker-engine/src/v4/rules/index.ts b/accessibility-checker-engine/src/v4/rules/index.ts
index f9430b5e7..d3988e786 100644
--- a/accessibility-checker-engine/src/v4/rules/index.ts
+++ b/accessibility-checker-engine/src/v4/rules/index.ts
@@ -175,6 +175,7 @@ export * from "./table_layout_linearized"
 export * from "./table_scope_valid"
 export * from "./table_structure_misuse"
 export * from "./table_summary_redundant"
+export * from "./target_spacing_sufficient"
 export * from "./text_block_heading"
 export * from "./text_contrast_sufficient"
 export * from "./text_quoted_correctly"
diff --git a/accessibility-checker-engine/src/v4/rules/target_spacing_sufficient.ts b/accessibility-checker-engine/src/v4/rules/target_spacing_sufficient.ts
index 4c8311f7f..7993bc346 100644
--- a/accessibility-checker-engine/src/v4/rules/target_spacing_sufficient.ts
+++ b/accessibility-checker-engine/src/v4/rules/target_spacing_sufficient.ts
@@ -50,7 +50,7 @@
         act: [],
         run: (context: RuleContext, options?: {}, contextHierarchies?: RuleContextHierarchy): RuleResult | RuleResult[] => {
             const ruleContext = context["dom"].node as HTMLElement;
-            if (!VisUtil.isNodeVisible(ruleContext) || (!RPTUtil.isTabbable(ruleContext) && !ruleContext .hasAttribute("tabindex")))
+            if (!VisUtil.isNodeVisible(ruleContext) || (!RPTUtil.isTarget(ruleContext)))
                 return null;
             
             const nodeName = ruleContext.nodeName.toLocaleLowerCase(); 
diff --git a/accessibility-checker-engine/test/v2/checker/accessibility/rules/target_spacing_sufficient_ruleunit/block_element_inline.html b/accessibility-checker-engine/test/v2/checker/accessibility/rules/target_spacing_sufficient_ruleunit/block_element_inline.html
new file mode 100755
index 000000000..204c8c8dc
--- /dev/null
+++ b/accessibility-checker-engine/test/v2/checker/accessibility/rules/target_spacing_sufficient_ruleunit/block_element_inline.html
@@ -0,0 +1,116 @@
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
+
+<!--
+   /******************************************************************************
+     Copyright:: 2020- IBM, Inc
+
+    Licensed under the Apache License, Version 2.0 (the "License");
+    you may not use this file except in compliance with the License.
+    You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+    Unless required by applicable law or agreed to in writing, software
+    distributed under the License is distributed on an "AS IS" BASIS,
+    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+    See the License for the specific language governing permissions and
+    limitations under the License.
+  *****************************************************************************/
+-->
+
+<html lang="en">
+
+<head>
+	<title>RPT Test Suite</title>
+  <style>
+    a.link {
+      display: inline; /* the default for a */
+      width: 100px;
+      height: 100px;
+      padding: 5px;
+    }
+
+    button.btn {
+      display: inline;
+      width: 100px;
+      height: 100px;
+      padding: 5px;
+    }
+
+    button.btn2 {
+      display: inline-block;
+      width: 100px;
+      height: 100px;
+      padding: 5px;
+      border: 1px solid blue;    
+      background-color: yellow; 
+    }
+
+    p {
+      display: block;
+      width: 100px;
+      height: 100px;
+      padding: 5px;
+      border: 1px solid blue;    
+      background-color: yellow; 
+    }
+  </style>
+</head>
+
+<body>
+
+  <h1>The display Property</h1>
+
+<h2>display: inline</h2>
+<div>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vestibulum consequat scelerisque elit sit amet consequat. Aliquam erat volutpat. <a class='link' href="google.com">Aliquam</a> <button class='btn' value='venenatis'></button> gravida nisl sit amet facilisis. Nullam cursus fermentum velit sed laoreet. </div>
+
+<h2>display: inline-block</h2>
+<div>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vestibulum consequat scelerisque elit sit amet consequat. Aliquam erat volutpat. <span class="b">Aliquam</span> <span class="b">venenatis</span> gravida nisl sit amet facilisis. Nullam cursus fermentum velit sed laoreet. </div>
+
+<h2>display: block</h2>
+<div>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vestibulum consequat scelerisque elit sit amet consequat. Aliquam erat volutpat. <span class="c">Aliquam</span> <span class="c">venenatis</span> gravida nisl sit amet facilisis. Nullam cursus fermentum velit sed laoreet. </div>
+
+  
+
+<script>
+  UnitTest = {
+    ruleIds: ["element_tabbable_unobscured"],
+    results: [
+    {
+            "ruleId": "element_tabbable_unobscured",
+            "value": [
+              "INFORMATION",
+              "POTENTIAL"
+            ],
+            "path": {
+              "dom": "/html[1]/body[1]/div[1]",
+              "aria": "/document[1]"
+            },
+            "reasonId": "potential_obscured",
+            "message": "Confirm that when the element receives focus, it is not covered or, if covered by user action, can be uncovered without moving focus",
+            "messageArgs": [],
+            "apiArgs": [],
+            "category": "Accessibility"
+          },
+          {
+            "ruleId": "element_tabbable_unobscured",
+            "value": [
+              "INFORMATION",
+              "PASS"
+            ],
+            "path": {
+              "dom": "/html[1]/body[1]/div[2]",
+              "aria": "/document[1]"
+            },
+            "reasonId": "pass",
+            "message": "The element is not entirely covered by other content",
+            "messageArgs": [],
+            "apiArgs": [],
+            "category": "Accessibility"
+          }
+    ]
+  }
+  </script>
+</body>
+
+</html>
diff --git a/accessibility-checker-engine/test/v2/checker/accessibility/rules/target_spacing_sufficient_ruleunit/element_inline.html b/accessibility-checker-engine/test/v2/checker/accessibility/rules/target_spacing_sufficient_ruleunit/element_inline.html
new file mode 100755
index 000000000..013531b8e
--- /dev/null
+++ b/accessibility-checker-engine/test/v2/checker/accessibility/rules/target_spacing_sufficient_ruleunit/element_inline.html
@@ -0,0 +1,121 @@
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
+
+<!--
+   /******************************************************************************
+     Copyright:: 2020- IBM, Inc
+
+    Licensed under the Apache License, Version 2.0 (the "License");
+    you may not use this file except in compliance with the License.
+    You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+    Unless required by applicable law or agreed to in writing, software
+    distributed under the License is distributed on an "AS IS" BASIS,
+    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+    See the License for the specific language governing permissions and
+    limitations under the License.
+  *****************************************************************************/
+-->
+
+<html lang="en">
+
+<head>
+	<title>RPT Test Suite</title>
+  <style>
+    a.link {
+      display: inline; /* the default for a */
+      width: 100px;
+      height: 100px;
+      line-height: 100px;
+      padding: 5px;
+    }
+
+    button.btn {
+      display: inline;
+      /**width: 100px;
+      height: 100px;
+      padding: 5px;*/
+    }
+
+    button.btn2 {
+      display: inline-block;
+      width: 100px;
+      height: 100px;
+      padding: 5px;
+      border: 1px solid blue;    
+      background-color: yellow; 
+    }
+
+    p {
+      display: block;
+      width: 100px;
+      height: 100px;
+      padding: 5px;
+      border: 1px solid blue;    
+      background-color: yellow; 
+    }
+  </style>
+</head>
+
+<body>
+
+  <h1>The display Property</h1>
+
+<h2>display: inline</h2>
+<div>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vestibulum consequat scelerisque elit sit amet consequat. Aliquam erat volutpat. 
+  <a class='link' href="google.com">Aliquam</a> 
+  <button class='btn' value='venenatis'></button> 
+  gravida nisl sit amet facilisis. Nullam cursus fermentum velit sed laoreet. 
+</div>
+
+<h2>display: inline-block</h2>
+<div>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vestibulum consequat scelerisque elit sit amet consequat. Aliquam erat volutpat. <span class="b">Aliquam</span> <span class="b">venenatis</span> gravida nisl sit amet facilisis. Nullam cursus fermentum velit sed laoreet. </div>
+
+<h2>display: block</h2>
+<div>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vestibulum consequat scelerisque elit sit amet consequat. Aliquam erat volutpat. <span class="c">Aliquam</span> <span class="c">venenatis</span> gravida nisl sit amet facilisis. Nullam cursus fermentum velit sed laoreet. </div>
+
+  
+
+<script>
+  UnitTest = {
+    ruleIds: ["element_tabbable_unobscured"],
+    results: [
+    {
+            "ruleId": "element_tabbable_unobscured",
+            "value": [
+              "INFORMATION",
+              "POTENTIAL"
+            ],
+            "path": {
+              "dom": "/html[1]/body[1]/div[1]",
+              "aria": "/document[1]"
+            },
+            "reasonId": "potential_obscured",
+            "message": "Confirm that when the element receives focus, it is not covered or, if covered by user action, can be uncovered without moving focus",
+            "messageArgs": [],
+            "apiArgs": [],
+            "category": "Accessibility"
+          },
+          {
+            "ruleId": "element_tabbable_unobscured",
+            "value": [
+              "INFORMATION",
+              "PASS"
+            ],
+            "path": {
+              "dom": "/html[1]/body[1]/div[2]",
+              "aria": "/document[1]"
+            },
+            "reasonId": "pass",
+            "message": "The element is not entirely covered by other content",
+            "messageArgs": [],
+            "apiArgs": [],
+            "category": "Accessibility"
+          }
+    ]
+  }
+  </script>
+</body>
+
+</html>