src/HOL/SPARK/Manual/document/loop_invariant.ads

clarified NEWS: document_files are officially required since Isabelle2014, but the absence was tolerated as legacy feature;

package Loop_Invariant
is

   type Word32 is mod 2 ** 32;

   procedure Proc1 (A : in Natural; B : in Word32; C : out Word32);
   --# derives C from A, B;
   --# post Word32 (A) * B = C;

   procedure Proc2 (A : in Natural; B : in Word32; C : out Word32);
   --# derives C from A, B;
   --# post Word32 (A) * B = C;

end Loop_Invariant;