Example

Consider the following syntactic definition.
EXAMple $<$string$>$ { $<$example-statement$>$ } END
$<$example-statement$>$:==
CHARge=$<$real$>$
EXCLude=( { $<$atom$>$ } )
MASS=$<$real$>$
TESTing=A1 $\vert$ A2 $\vert$ A3
TYPE=$<$type$>$
$<$string$>$:==
any sequence of four characters.
The following input lines are possibilities for valid constructs:
example A type=ABCD  mass=30.0 end
example B type=BBBB  charge=5.0  exclude=( A B C D ) end
example C charge=5. mass=40.0  type=XXX   testing=A3 end
example D end



Xplor-NIH 2023-11-10