The Syntaxer checks the request parcel for high-level syntax. If no errors are detected, the Syntaxer converts the request parcels into a skeletal parse tree called the SynTree or Black Tree. When this process completes, the Parser passes the SynTree to the DPL component (see Dynamically Parameterized Requests), and then to the Resolver.
A parse tree is a data structure used by the SQL Parser to represent a request parcel in a form that is simple to annotate with descriptive and statistical information derived from the Data Dictionary and from derived statistics.
The parse tree also permits a relatively simple transformation of the request parcel by Query Rewrite and the Optimizer into an execution plan.