3 files changed, 58 insertions, 4 deletions

diff --git a/src/api/wix/WixToolset.Extensibility/Data/BundleVariableNameRule.cs b/src/api/wix/WixToolset.Extensibility/Data/BundleVariableNameRule.cs
new file mode 100644
index 00000000..eb6f7543
--- /dev/null
+++ b/src/api/wix/WixToolset.Extensibility/Data/BundleVariableNameRule.cs
@@ -0,0 +1,33 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information.
+
+namespace WixToolset.Extensibility.Data
+{
+    using System;
+
+    /// <summary>
+    /// When validating a bundle variable name, which special restrictions to ignore.
+    /// </summary>
+    [Flags]
+    public enum BundleVariableNameRule
+    {
+        /// <summary>
+        /// Enforce all special restrictions.
+        /// </summary>
+        EnforceAllRestrictions = 0x0,
+
+        /// <summary>
+        /// Allow names of built-in variables.
+        /// </summary>
+        CanBeBuiltIn = 0x1,
+
+        /// <summary>
+        /// Allow names of well-known variables.
+        /// </summary>
+        CanBeWellKnown = 0x2,
+
+        /// <summary>
+        /// Allow names that are not built-in and are not well-known and start with 'Wix'.
+        /// </summary>
+        CanHaveReservedPrefix = 0x4,
+    }
+}
diff --git a/src/api/wix/WixToolset.Extensibility/Services/IBundleValidator.cs b/src/api/wix/WixToolset.Extensibility/Services/IBundleValidator.cs
index 43f65fc8..3753d16d 100644
--- a/src/api/wix/WixToolset.Extensibility/Services/IBundleValidator.cs
+++ b/src/api/wix/WixToolset.Extensibility/Services/IBundleValidator.cs
@@ -33,15 +33,35 @@ namespace WixToolset.Extensibility.Services
         bool ValidateBundleMsiPropertyName(SourceLineNumber sourceLineNumbers, string elementName, string attributeName, string propertyName);
 
         /// <summary>
-        /// Validates a Bundle variable name and displays an error for an illegal value.
+        /// Validates a Bundle variable name that is being used to declare a Variable in the bundle manifest and displays an error for an illegal value.
         /// </summary>
         /// <param name="sourceLineNumbers"></param>
         /// <param name="elementName"></param>
         /// <param name="attributeName"></param>
         /// <param name="variableName"></param>
-        /// <param name="allowBuiltIn">Whether to bypass checks for reserved values.</param>
         /// <returns>Whether the name is valid.</returns>
-        bool ValidateBundleVariableName(SourceLineNumber sourceLineNumbers, string elementName, string attributeName, string variableName, bool allowBuiltIn);
+        bool ValidateBundleVariableNameDeclaration(SourceLineNumber sourceLineNumbers, string elementName, string attributeName, string variableName);
+
+        /// <summary>
+        /// Validates a Bundle variable name that is being used to reference a Variable and displays an error for an illegal value.
+        /// </summary>
+        /// <param name="sourceLineNumbers"></param>
+        /// <param name="elementName"></param>
+        /// <param name="attributeName"></param>
+        /// <param name="variableName"></param>
+        /// <param name="nameRule"></param>
+        /// <returns>Whether the name is valid.</returns>
+        bool ValidateBundleVariableNameValue(SourceLineNumber sourceLineNumbers, string elementName, string attributeName, string variableName, BundleVariableNameRule nameRule);
+
+        /// <summary>
+        /// Validates a Bundle variable name that is being used to set its value and displays an error for an illegal value.
+        /// </summary>
+        /// <param name="sourceLineNumbers"></param>
+        /// <param name="elementName"></param>
+        /// <param name="attributeName"></param>
+        /// <param name="variableName"></param>
+        /// <returns>Whether the name is valid.</returns>
+        bool ValidateBundleVariableNameTarget(SourceLineNumber sourceLineNumbers, string elementName, string attributeName, string variableName);
 
         /// <summary>
         /// Validates a bundle condition and displays an error for an illegal value.
diff --git a/src/api/wix/WixToolset.Extensibility/Services/IParseHelper.cs b/src/api/wix/WixToolset.Extensibility/Services/IParseHelper.cs
index a8246b9b..3a3c2ceb 100644
--- a/src/api/wix/WixToolset.Extensibility/Services/IParseHelper.cs
+++ b/src/api/wix/WixToolset.Extensibility/Services/IParseHelper.cs
@@ -246,8 +246,9 @@ namespace WixToolset.Extensibility.Services
         /// </summary>
         /// <param name="sourceLineNumbers">Source line information about the owner element.</param>
         /// <param name="attribute">The attribute containing the value to get.</param>
+        /// <param name="nameRule">A rule for the contents of the value. If the contents do not follow the rule, an error is thrown.</param>
         /// <returns>The attribute's value.</returns>
-        string GetAttributeBundleVariableNameValue(SourceLineNumber sourceLineNumbers, XAttribute attribute);
+        string GetAttributeBundleVariableNameValue(SourceLineNumber sourceLineNumbers, XAttribute attribute, BundleVariableNameRule nameRule = BundleVariableNameRule.CanBeWellKnown | BundleVariableNameRule.CanHaveReservedPrefix);
 
         /// <summary>
         /// Get a guid attribute value and displays an error for an illegal guid value.