Create README.md

Author: mandeepkaran

Core ServiceNow APIs/GlideElement/Smart Field Validation and Dependent Field Derivation Using getError() and setError()/README.md

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+# Smart Field Validation and Dependent Field Derivation Using GlideElement.getError()
+
+This project demonstrates how to use `GlideElement.setError()` and `GlideElement.getError()` 
+to perform validation in one Business Rule and field derivation in another, without repeating logic.
+
+## 📘 Overview
+
+This snippet demonstrates how to share validation state and error messages between multiple Business Rules using `GlideElement.setError()` and `GlideElement.getError()` in ServiceNow.
+
+By propagating validation context across Business Rules, developers can:
+
+- Avoid repeated validation logic.  
+- Trigger dependent field updates only when a field passes validation.  
+- Maintain consistent and clean data flow between sequential rules.  
+
+This technique is especially useful when different validation or derivation rules are split by purpose or owned by different teams.
+
+---
+
+## 🧠 Concept
+
+When one Business Rule sets an error on a field using `setError()`, the error message persists in memory for that record during the same transaction.  
+A later Business Rule (executing at a higher order) can then retrieve that message using `getError()` and make data-driven decisions.
+
+### Flow:
+1. BR #1 (`Validate Short Description`) checks text length.
+2. BR #2 (`Derive Dependent Fields`) runs only if no validation error exists.
+3. Category, Subcategory, and Impact are derived dynamically.
+
+## 🚀 Benefits
+
+- ✅ Reduces redundant validation checks
+- ✅ Improves rule execution efficiency
+- ✅ Keeps logic modular and maintainable
+- ✅ Provides better visibility and control in field validations