KB: Resolving Undeclared Identifier Error in Altium

Solution Details

Error Message

When applying design rules in Altium, you may encounter an error stating: “Undeclared Identifier: [query identifier] at Line ##, Char: $$$.” This indicates that the query used in the rule is invalid or references an undefined identifier.

Common Cause of the Error

• The query syntax is incorrect or contains typos.
• The identifier (e.g., HasFootprint) is not recognized because it is not defined in the current context.
• The rule scope is improperly set, causing Altium to fail in applying the condition.

Resolution

To resolve the issue:

• Verify that all design rule queries are correctly written and valid.
• Check for rules highlighted in red, as these indicate incorrect definitions.
  
• Test each query individually to confirm it returns valid results.

Step-by-Step Instructions

1. Open PCB Rules and Constraints Editor in Altium.
2. Navigate to the rule that triggered the error.
3. Review the query in the Scope field:
   • Ensure the syntax matches Altium’s query language.
   • Correct any typos or undefined identifiers.
4. Use the Query Builder or Query Test feature:
   • Test the query to confirm it returns valid objects.
   • If the query fails or displays in red, adjust it until valid.
5. Apply changes and revalidate the design rules.

Additional Notes

• Common identifiers like HasFootprint must be used correctly; refer to Altium’s query syntax documentation for guidance.
• Always validate queries before applying them to avoid compilation errors.