integer ::= digit {[underline] digit}
12
0
1E6
123_456
-- integer literals
12.0
0.0
0.456
3.14159_26
-- real literals
1.34E-12
1.0E+6
-- real literals with exponent
base # based_integer [.based_integer] # [exponent]
base ::= integer
extended_digit {[underline] extended_digit}
2#1111_1111#
16#FF# 016#0FF#
-- integer literals
-- of value 255
6#E#E1
2#1110_0000 #
-- integer literals
-- of value 224
16#F.FF#E+2
2#1.1111_1111_111#E11
-- real literals
-- of value 4095.0