The heading levels are incorrect on the page:

1. Summary Table
2. Introduction
3. Handling Errors
4. Standard Parameters
   1. Parameters for all resources
   2. Parameters for each resource
   3. Search Parameter Types
   4. Modifiers
   5. Prefixes
   6. number
   7. date
   8. string
   9. uri
   10. token
       1. Searching Mime Types
   11. quantity
   12. reference
   13. References and Versions
   14. Searching Hierarchies
   15. Chained parameters
   16. Reverse Chaining
   17. Composite Search Parameters
   18. Handling Missing Data
   19. Escaping Search Parameters
   20. Text Search Parameters
   21. Special Parameters
   22. Searching by list
   23. Advanced filtering
   24. Specifying the type of Resource
5. Managing Returned Resources
   1. Sorting
   2. Page Count
   3. Including other resources in result (_include and _revinclude)
   4. Contained Resources
   5. External References
   6. Paging
   7. Summary
   8. Elements
   9. Relevance
6. Server Conformance
7. Advanced Search
8. Search Result Currency
9. Summary Tables

Suggestions:

• 'References and Versions' through 'Specifying the type of Resource' should be one level higher (e.g., not children of 'Standard Parameters').
• Since composite is a type, it should be with the other types.
• Heading capitalization fixes (e.g., Mime -> MIME, same levels having the same indentation, etc.).
• Given the length of the page, add a ToC with top-level headings