The inline declaration "DATA(FOO)" is not possible in this position.

Hello,

I want to use the new DATA inline-declarations in the SCAN SOURCE statement as follows:

SCAN ABAP-SOURCE source_lines
  TOKENS INTO DATA(tokens)
  STATEMENTS INTO DATA(stmts).

However the following error is given: "The inline declaration "DATA(TOKENS)" is not possible in this position."

Why is this not possible?