diff --git a/PROMS/Volian.Controls.Library/DisplayApplicability.cs b/PROMS/Volian.Controls.Library/DisplayApplicability.cs
index 8b9d460b..48b7003e 100644
--- a/PROMS/Volian.Controls.Library/DisplayApplicability.cs
+++ b/PROMS/Volian.Controls.Library/DisplayApplicability.cs
@@ -5,6 +5,7 @@ using System.Collections.Generic;
 using System.ComponentModel;
 using System.Data;
 using System.Drawing;
+using System.Linq;
 using System.Text;
 using System.Windows.Forms;
 using VEPROMS.CSLA.Library;
@@ -225,8 +226,8 @@ namespace Volian.Controls.Library
 			//	return internal and external for the procedure level)
 			if ((!MyItemInfo.IsProcedure && invalidTrans.Count == 0) || IsProcWithNoExternalTrans(MyItemInfo, invalidTrans))
 			{
-				// C2021 - 027: Procedure level PC/PC
-				if (MyItemInfo.IsProcedure && MyItemInfo.ActiveFormat.PlantFormat.FormatData.ProcData.ProcAppl)
+                // C2021 - 027: Procedure level PC/PC
+                if (MyItemInfo.IsProcedure && MyItemInfo.ActiveFormat.PlantFormat.FormatData.ProcData.ProcAppl)
 				{
 					ProcedureConfig sc = MyItemInfo.MyConfig as ProcedureConfig;
 					sc.MasterSlave_Applicability = Volian.Base.Library.BigNum.MakeBigNum(MyApplicability);
@@ -284,26 +285,56 @@ namespace Volian.Controls.Library
 			Volian.Base.Library.BigNum MasterSlave_ApplicabilityTmp;
 			StepConfig sc = MyItemInfo.MyConfig as StepConfig;
 			MasterSlave_ApplicabilityTmp = sc.MasterSlave_Applicability;
+            StringBuilder sb = new StringBuilder();
 
-			ItemInfo startitm = MyItemInfo.FirstSibling;
+
+            ItemInfo startitm = MyItemInfo.FirstSibling;
 			while (startitm != null)
 			{
-				StepConfig sc2 = startitm.MyConfig as StepConfig;
-				using (Content cnt = Content.Get(startitm.MyContent.ContentID))
-				{
-					sc2.MasterSlave_Applicability = (MasterSlave_ApplicabilityTmp);
-					cnt.Config = sc2.ToString();
-					cnt.Save();
+
+                // C2026-023: Check for Transitions when setting Applicability to all for a level
+                List<InvalidTransition> invalidTrans = WillTransitionsBeValidCommand.Execute(startitm.ItemID, MasterSlave_ApplicabilityTmp.ToString());
+                if (IsProcWithNoExternalTrans(startitm, invalidTrans))
+                {
+                    StepConfig sc2 = startitm.MyConfig as StepConfig;
+                    using (Content cnt = Content.Get(startitm.MyContent.ContentID))
+                    {
+                        sc2.MasterSlave_Applicability = (MasterSlave_ApplicabilityTmp);
+                        cnt.Config = sc2.ToString();
+                        cnt.Save();
+                    }
 				}
+                else
+                {
+					if (sb.Length == 0)
+					{
+                        sb.AppendLine("The applicability for some Step(s) cannot be changed due to transition links.");
+                        sb.AppendLine("Applicability settings for these steps will return to original settings when OK is selected.");
+                        sb.AppendLine("Changing the applicability for would invalidate a transition in the following steps:");
+                        sb.AppendLine();
+                    }
+
+                    foreach (InvalidTransition inv in invalidTrans.Where(x => !x.TgtStep.StartsWith(x.SrcStep)))
+                    {
+                        sb.AppendLine(string.Format("{0} : From {1} to {2}.", startitm.MyTab.CleanTextNoSymbols.Trim(), inv.TgtStep, inv.SrcStep));
+                    }
+
+                    invalidTrans.Clear();
+                }
+
 				startitm = startitm.GetNext();
 			}
 
 			_MyDisplayTabItem.MyStepTabPanel.MyStepTabRibbon.RefreshProcedure();
 
-		}
+            if (sb.Length > 0)
+				FlexibleMessageBox.Show(sb.ToString(), "Transitions Affected By Applicability Change");
 
-		// B2021-149: for procedure, only consider external transitions as invalid
-		private bool IsProcWithNoExternalTrans(ItemInfo ii, List<InvalidTransition> invalidTrans)
+
+        }
+
+        // B2021-149: for procedure, only consider external transitions as invalid
+        private bool IsProcWithNoExternalTrans(ItemInfo ii, List<InvalidTransition> invalidTrans)
 		{
 			if (invalidTrans.Count == 0) return true;
 			foreach (InvalidTransition iT in invalidTrans)