XBNF
extrinsic-prefix -to -rule
to to is EXTRINSIC ( extrinsic-kind-keyword )
extrinsic-kind-keyword -to -rule
to to is HPF
-to or HPF_LOCAL
-to or HPF_SERIAL
program-stmt -to -rule
to to is [ extrinsic-prefix ] PROGRAM program-name
module-stmt -to -rule
to to is [ extrinsic-prefix ] MODULE module-name
block-data-stmt -to -rule
to to is [ extrinsic-prefix ] BLOCK DATA block-data-name
XBNF