Appendix A: Hark Grammar
The grammar used in the voice recognition system is described below in
standard Backus-Naur notation. Numbers in the range from 1 to 99,999
were recognized by this grammar. In addition, simple variations on
the normal pronunciation were allowed, such as "forty-two thousand and
one hundred" for "forty-two thousand, one hundred." Encompassing
these variations improved flexibility and thus improved the accuracy
of the recognition system.
NUMBER => [ (TENNUMBER | DIGIT) thousand] and
[DIGIT hundred] and [TENNUMBER]
TENNUMBER => TENS | DIGIT
TENS => TENSXTY DIGIT | TENSXTY | TEENS
TENSXTY => twenty | thirty | forty | fifty | sixty | seventy | eighty | ninety
TEENS => ten | eleven | twelve | thirteen | fourteen | fifteen | sixteen | seventeen | eighteen | nineteen
DIGIT => one | two | three | four | five | six | seven | eight | nine
On to next section: Appendix B