I'm creating an extremely difficult challenge that combines multiple complex pattern types that will require sophisticated regex techniques. This challenge includes:
1. Product codes with specific formats but tricky variations
2. Valid IPv6 addresses (partial and complete) mixed with similar invalid formats
3. Custom data formats that superficially resemble the valid patterns
4. Items requiring negative lookahead/lookbehind to properly identify
5. Patterns with special characters that need caref... (truncated)