I guess there is no short answer to that question, as the SQL standard is such a huge collection of obligatory and optional features. The general rule can be found in the SQL dialects and compatibility topic:

SQL Anywhere complies with the SQL-92-based United States Federal Information Processing Standard Publication (FIPS PUB) 127. With minor exceptions, SQL Anywhere is compliant with the ISO/ANSI SQL/2008 core specification as documented in the 9 parts of ISO/IEC JTC 1/SC 32 9075-2008. Information about compliance is provided in the reference documentation for each feature of SQL Anywhere.

That is, for each SQL Anywhere statement, you will find a "Standards and compatibility" section describing whether and in what degree the statement fits the SQL/2008 standard, cf. here for the SELECT statement:

SQL/2008 Core feature. The complexity of the SELECT statement means that you should check individual clauses against the standard. For example, the ROLLUP keyword, which can be specified in a GROUP BY clause, is part of optional SQL/2008 language feature T431. Some of the SQL/2008 optional language features supported by SQL Anywhere include:

• The WINDOW clause and WINDOW aggregate functions comprise optional SQL/2008 language features T611 and T612.
  
• Sequence expressions are part of feature T176.
  ...

Furthermore, you can use the SQLFLAGGER() builtin function to check individual statements against several SQL standard versions.