I'm creating an extraordinarily difficult challenge that combines:
1. Nested structures with balanced delimiters and escaped characters
2. Complex date-time patterns with fractional seconds and various timezone formats
3. Mixed protocol URIs with special characters and IPv6 literals
4. Mathematical expressions with LaTeX-style notation
5. Custom identifiers with specific format requirements
6. Look-alike patterns that should not match
The text includes similar-looking patterns that aren't part o... (truncated)